Renaming to plushu-git-apps

[stuartpb]

Especially after plushu/plushu-git#5, this plugin is becoming increasingly responsible for all the components of managing apps' integration with Git, and if plushu/plushu-apps#4 goes through, they won't just be things that happen when receiving.

[stuartpb]

Wait, no, plushu/plushu-apps#4 wouldn't have anything to do with this (it affects release and deployment plugins). Still, though, in refactoring plans, this plugin has repeatedly come within a whisker to taking on one kind of responsibility or another for apps beyond just receiving them. "plushu-git-apps" is starting to sound just plain reasonable.

As an example of how this plugin's scope is growing to be inaccurate, let's consider the possibility that I add another way to get apps via Git (probably via clone). If I could genericize that method and leave the implementation to plugins, I'd add it to this one rather than crafting another "plushu-git-something-app" plugin (since putting it as a feature of hooks makes it harmless if the equivalent method isn't installed).

Basically, the name change would reflect a more current view of how plugins are meant to be factored, where "plushu-git-receive-app" is more an artifact of the Dokku-based thought patterns in the original design (when the name was chosen to add specificity for other alternatives to the "receive" command plugin).

The name change will also make it dissimilar from git-receive-init and git-receive-warn-no-master, two verb-based plugin descriptions.

[stuartpb]

Okay, you know what, let's do this: I'll rename this plugin when plushu-git-hooking gets renamed to plushu-git.