support for contenteditable ui elements
make title editable in place

in the navbar: fixes #94
of the current notebook in notebook tree: fixes #252
Merge branch 'feature/edit-title-in-place' into develop
Merge branch 'develop' into feature/rserve-js-new-callback

Conflicts:
	htdocs/editor_tab.js
	htdocs/js/rcloud_bundle.min.js
minor cleanups on promise refaxtor; fix selection
fix more promise stuff / use more cool bluebird features
fix in-place editing of title of notebook with history
remember you *promised* to return stuff...
contenteditable glitch on going back to current version
history button open if closed (not hide)
must.. use.. more.. bluebird features
missing return values in promises
more bluebird features
artifacts
update rserve-js submodule