#25588 Install commands support dev descriptors

Adds support for dev descriptors to the install_app and install_engine commands. Also added a tweak so that if you are launching a UI from an app with a dev descriptor, a small DEV suffix will be appended to the title to help developers keep track of which apps are in dev mode.
![screen shot 2014-06-05 at 11 48 43](https://cloud.githubusercontent.com/assets/337710/3186743/588fc5a6-eca7-11e3-812c-591ec81a0f66.png)