Bug 1012981 - Generate unique password and show it to the user

Replaces the static password to more secure unique, generated password and shows it to the user:
* when creates the application from the web ui
* when creates the app with `rhc app create --from-app [...]`
* when creates the cartridges and pushes the quickstart via git

Also add instructions in case of web ui timeout

[Bug 1012981](https://bugzilla.redhat.com/show_bug.cgi?id=1012981) (and also [related](https://bugzilla.redhat.com/show_bug.cgi?id=1013684))
@vbalazs  Would be ok if we had a clean way to know whether this was the first build.  Using a file isn't perfect because we in theory could switch to another haproxy gear to do the build next time.

@bparees @mfojtik Can you think of a cleaner way to check for the first build?