wip-add commands

@mlynch - Please review.

Now adds a few more commands for the ionic CLI:

`ionic add underscore`
`ionic rm underscore` or `ionic remove underscore`

These install the bower components or remove them.

`ionic service add deploy`
* installs the ionic-service-deploy component
* scans the installed package's `ionic-plugins.json` file
* for each plugin listed in the file, it runs `ionic plugin add <plugin>`

`ionic service remove deploy`
* gets the packages `ionic-plugins.json` file 
* removes the package
* removes the plugins that were required by the plugin 

**NOTES**
* Some of the bower packages were not deployed yet, so `bower link` is used - needing to be switched to `bower install` once they are ready.
* execSync package is still used - untested on windows.