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))

[Trello card](https://trello.com/c/RsENlXNV/257-5-fix-5-existing-bugs)
I'm not totally clear on the issue here, but can we define an env variable the user can set which will be used for the password, if present?  Presumably that would allow the password to be shared between scaled instances.

The user would have to set that environment variable when creating the scaled app, for things to work.