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
Fix translator and promise handling

Fixes spec suite.
Merge pull request #555 from latin-language-toolkit/translator_spec

Fix translator and promise handling
Use unused variable in idHandler
Fix ellipsis problem in TreebankPersister

As uncovered by @balmas we were destroying our idMappings during the
handling of new artificialTokens. This was a refactoring gone wrong,
where an older code piece - not needed anymore - was still lingering
around.

We also declare the sentence unchanged after we updated it - this option
was formerly not used at all. If a sentence received changes in an
annotation session, it's changed property stayed true. This meant that
everytime another - unrelated - change was saved in the document, this
sentence would also be re-updated again.

Taking into account that our idMappings were destroyed at this point,
the nasty bug of losing ellided nodes surfaced.
Update persister spec for more realism
Add first artificial token spec in persister
Add second artificial token spec in persister
Minor spec fix
Update spec
Minor refactor in persister spec
Add sourceMap check