Fix background shading in arrival list

[kungharrison]

Fix for #451 regarding inconsistent background shading behind cards.

Changes:
arrivals_list_empty_style.xml: arrival_list_background background color was added to arrivals_list_empty_style.xml to add the background color properly when the arrival list is empty.
ArrivalsListFragment.java: Apply background color to root view of list view, this sets the arrival_list_background color properly to the entire area.

Screenshots:
Arrival List when empty before fix:

Arrival List when empty after fix:

Arrival List with content before fix:

Arrival List with content after fix:

Please make sure these boxes are checked before submitting your pull request - thanks!

• Apply the AndroidStyle.xml style template to your code in Android Studio.
• Run the unit tests with gradlew connectedObaGoogleDebugAndroidTest connectedObaAmazonDebugAndroidTest to make sure you didn't break anything
• If you have multiple commits please combine them into one commit by squashing them for the initial submission of the pull request. When addressing comments on a pull request, please push a new commit per comment when possible (reviewers will squash and merge using GitHub merge tool)

[aaronbrethorst]

Hi @kungharrison - Apologies for not responding to your PR until now! I thought I had notifications turned on for this repo, but I guess I don't 🥲

I'll review this soon and let you know if I have any feedback. much obliged!

[kungharrison]

@aaronbrethorst Thanks! I've been using this app for a while, so I thought I would contribute. This is my first PR as well so let me know if there are any issues.

[aaronbrethorst]

looks great! 🚀

[aaronbrethorst]

@kungharrison 2.11.1, which includes this change, was just published in the Play Store. Thanks again! Also, please reach out to me at [email protected]. I'd love to add you to our Slack group.

[kungharrison]

Also I believe we can now close issue #241

[aaronbrethorst]

@kungharrison I think you mean #451, but I have now closed it :)