Activate and deactivate plugins

[luisherranz]

First, let's create a plugin and work on activation and deactivation of plugins in both the dashboard and the app.

[luisherranz]

First step working, package activations:
5aa163d

[luisherranz]

Package deactivations working:
35664bb

Things left:

• Create a Saga to listen to 'removed' and deactivate sagas and reducers.