Improve update indicator

For now, the only way to update an application is to click on the “Update available” button displayed:

if a new version of the application is available;
if the application is not installed on the master branch. This allows developers to update an app without having to upgrade version number ;

Unfortunately, the default branch of some application is not master. Some applications ported on Cozy use a cozy branch as default. So users never know if an update is really available. And every time they update, the “Update available” keeps displaying, like if the update didn't work.

We should find a better way to allow developers to update their applications, without always pretending that an update is available.

One way would be to display a small “force update” button on applications whose branch is not “master”, but it's a little bit hacky.

Another way would be to add in the manifest a defaultBranch field, and display this update button if current installed branch is different from the default one.

cozy / cozy-home-v2

Improve update indicator #658