Merge pull request #941 from twosigma/ildipo/minorstuff

Ildipo/minorstuff
Resolve Issue #942 by recording the PID in ~/.beaker on startup
Added to bkHelper functions to operate on notebook cells from JavaScript
cells. Now you can get the evaluator list, get code cells, set the body,
evaluator and tags og other code cells.
Merge pull request #943 from twosigma/spot/942

Resolve Issue #942 by recording the PID in ~/.beaker on startup
Implemented notebook control rest API and exposed to JVM based languages
protect evaluators that can execute only one request at a time from.
properly handle evaluation error(s)
properly deserialize evaluation results
Cleanup some exceptions on some functions.
Cleanup of debugging messagges.
Rebuild tag map when changing tags from Cell Options UI.
Added new example notebooks (and reworked others).
Added example file for control and reflection API.
Reworked form example.
Now in JavaScript you can access the useful bkHelper function via the
beaker object, like it is done in other languages.
Now you can access the beaker object also in Html-embedded scripts.
Merge remote-tracking branch 'origin/master' into
ildipo/notebookmodelaccess
Added banner.
Some cleanup of cut and paste code
Merge pull request #952 from twosigma/ildipo/notebookmodelaccess

Ildipo/notebookmodelaccess
add opacity 0.999 to the code mirror editor, which has no practical effect on its appearance, but it does change the stacking group so it doesnot block the cell menu, hence fixing Issue #951
Merge pull request #953 from twosigma/spot/951

add opacity 0.999 to the code mirror editor, which has no practical effe...