Add analytics event for the save button
Add category and label for save event tracking
Change declarative to programmatic tracking

Now we always know that save was called, but we don't know
how it was called.

We should also have an eye on the specs, because breaking the
morph specs by adding something to the saver seems a little strange.
Add analytics to exit handler
Move angulartics et al. to arethusa.core so that the specs work
Merge pull request #277 from latin-language-toolkit/analytics-events

Add analytics event for save button