Invalid justifyContent/borderRadius props on login components

[ErnWong]

Describe the bug

A borderRadius prop was passed to a Button which doesn't have such prop.

A2/split-webapp/split/src/pages/Login.js

Line 132 in c689d3c

borderRadius={30}

A justifyContent prop was passed to a Box which doesn't have such prop in the material ui version we are using.

A2/split-webapp/split/src/pages/Login.js

Line 82 in c689d3c

<Container fixed justifyContent="center">

To Reproduce
Steps to reproduce the behavior:

1. npm start the frontend to start it in development mode.
2. Go to the login page.
3. Open console.

Severity
Mark with an x.
[x]: Minor effect - not user facing, but indication of a fault needing to be fixed
[]: Functional error eg. App does not function correctly
[]: Severe eg. Crashing

Reproducibility
Mark with an x.
[x]: Consistent
[]: Occasional
[]: Cannot reproduce at the moment eg. unsure

Expected behavior
No errors shown. Hopefully have tests set up that ensure that these errors are caught before features are merged into master.

Screenshots, Images and Traces

Warning: React does not recognize the `justifyContent` prop on a DOM element. If you intentionally want it to appear in the DOM as a custom attribute, spell it as lowercase `justifycontent` instead. If you accidentally passed it from a parent component, remove it from the DOM element.
    in div (created by ForwardRef(Container))
    in ForwardRef(Container) (created by WithStyles(ForwardRef(Container)))
    in WithStyles(ForwardRef(Container)) (at Login.js:82)
    in div (created by ForwardRef(Grid))
    in ForwardRef(Grid) (created by WithStyles(ForwardRef(Grid)))
    in WithStyles(ForwardRef(Grid)) (at Login.js:81)
    in div (created by ForwardRef(Grid))
    in ForwardRef(Grid) (created by WithStyles(ForwardRef(Grid)))
    in WithStyles(ForwardRef(Grid)) (at Login.js:73)
    in Login (created by Context.Consumer)
    in Route (at App.js:14)
    in div (at App.js:13)
    in header (at App.js:12)
    in div (at App.js:11)
    in Router (created by HashRouter)
    in HashRouter (at App.js:10)
    in App (at src/index.js:6)

Warning: React does not recognize the `borderRadius` prop on a DOM element. If you intentionally want it to appear in the DOM as a custom attribute, spell it as lowercase `borderradius` instead. If you accidentally passed it from a parent component, remove it from the DOM element.
    in button (created by ForwardRef(ButtonBase))
    in ForwardRef(ButtonBase) (created by WithStyles(ForwardRef(ButtonBase)))
    in WithStyles(ForwardRef(ButtonBase)) (created by ForwardRef(Button))
    in ForwardRef(Button) (created by WithStyles(ForwardRef(Button)))
    in WithStyles(ForwardRef(Button)) (at Login.js:129)
    in h3 (created by ForwardRef(Typography))
    in ForwardRef(Typography) (created by WithStyles(ForwardRef(Typography)))
    in WithStyles(ForwardRef(Typography)) (at Login.js:128)
    in div (created by Styled(MuiBox))
    in Styled(MuiBox) (at Login.js:94)
    in div (created by Styled(MuiBox))
    in Styled(MuiBox) (at Login.js:84)
    in div (created by ForwardRef(Container))
    in ForwardRef(Container) (created by WithStyles(ForwardRef(Container)))
    in WithStyles(ForwardRef(Container)) (at Login.js:83)
    in div (created by ForwardRef(Container))
    in ForwardRef(Container) (created by WithStyles(ForwardRef(Container)))
    in WithStyles(ForwardRef(Container)) (at Login.js:82)
    in div (created by ForwardRef(Grid))
    in ForwardRef(Grid) (created by WithStyles(ForwardRef(Grid)))
    in WithStyles(ForwardRef(Grid)) (at Login.js:81)
    in div (created by ForwardRef(Grid))
    in ForwardRef(Grid) (created by WithStyles(ForwardRef(Grid)))
    in WithStyles(ForwardRef(Grid)) (at Login.js:73)
    in Login (created by Context.Consumer)
    in Route (at App.js:14)
    in div (at App.js:13)
    in header (at App.js:12)
    in div (at App.js:11)
    in Router (created by HashRouter)
    in HashRouter (at App.js:10)
    in App (at src/index.js:6)

Conditions
Ubuntu, Chromium/Firefox, material-ui 4.9.5 installed under /node_modules.

Issue Dependencies
TODO - Potentially another issue to refactor the styling code? I'm thinking that using Material-UI's styling solution would work quite well. That would provide modularity, theming, reuse of style parameters like colours, margins, etc.

Additional context
TODO