Fix the setup for local dev

[nathanaelhoun]

Describe the problem

When launching a new local development, a lot of steps are required

• installing the good version of node
• creating an empty database with mariadb
• running npm i
• importing an initial sql file for config and users
• creating a fake LDAP to connect to the app
• running npm start

Solution
There was a proposal of using Docker in #285 to make the startup straightforward. But this will introduce a lot of complexity for someone who is not familiar with containers.

So the new idea is to discard the work of #285 and the documentation and to work to ease the setup process:

• disabling LDAP connection on local dev
• automatic importation of config and users files at first startup
• gives the initial credentials to the developer (in the doc or in the server console)