Add list of Cordova plugins to `ionic info`

Cordova plugins or their versions often cause problems for building apps or running apps on specific devices (with specific Android versions). It would help a lot if `ionic info` would also output a list of the installed Cordova plugins and their versions.

Examples where this would help to solve things:
- cordova-plugin-ionic-webview on Android <5
- console plugin still installed with cordova-ios 4.5.x