Revert "Revert "Setup test""

This reverts commit fb8cf274a01ed81b0c239e32f2516333b1b27c6a.
Simplified test and made to work with polymer.
Testing annotations.  Working now with re-assignment to currentSession.annotations
created setAnnotation and removeAnnotation for setting and removing annotations (with annotation list hack).
TEMPORARY: Modified test to set and then remove annotation
Implemented so markers <-> annotations should be working except that .DELETE doesn't provide marker.  Will change to clear in the next commit
Fixed to nuke all markers rather than remove individually.
TESTING: Made testing button bigger
Added updateMarkers() method and moved the handler from the test code to initWorkspace.
updateMarkers is unnecessary
Remove testing
removed more testing
Removed ace package dependency in spark.dart
accessing private _workspace var instead of public during init.
Switched setAnnotations(annotation info) to setMarkers(List<Marker).  Changed severity types to all be ints
Cleanup git.js library.
Removed removeAnntation(...)
Simplified clearAnnotations()
Updated pub spec to require ace 1.6+
removed marker / annotation code in spark.dart to be added elsewhere.