Improve autocompletion

* Move build, livesync-cloud and prop commands to `commands`
* Implement completionData for build, livesync-cloud and prop commands

Should be merged after this https://github.com/telerik/mobile-cli-lib/pull/112
Helper PR for this story http://teampulse.telerik.com/view#item/280276
The if can be collapsed into ```return validationValue;```