Application creation workflow

[vincent-zurczak]

Today, creating an application is a direct thing.
You click an application template and fill-in a form to create a new application. This application is directly created.

In some environments, it may be necessary to delay the creation until it is validated.
Therefore, it should also be possible to ask the creation of an application from a template. The request would then follow a validation workflow: accepted, rejected and suspended.

All of this should be mapped with the roles / permissions. See #643.