Worked on annotation editor. Rectoring, Tag labels above spectrograms, and unit conversions.
Also fixed the too many notifications drawABox-watchers-events-circular bug

modified:   Gemfile
modified:   Gemfile.lock
	-- updated rails version

modified:   app/assets/javascripts/angular/controllers/annotation_viewer.js
	-- added constructor function for Annotations, moved converters inside (easy access to scope), and added a provision for tag acccess.

modified:   app/assets/javascripts/angular/controllers/listen.js
	-- added transformation success function for ensuring consistency of data returned from server.

modified:   app/assets/javascripts/angular/directives/directives.js
	-- refactored, and fixed the infinite update bug caused by an oversealous watcher

modified:   app/assets/templates/annotation_viewer.html
modified:   app/assets/stylesheets/_annotation_viewer.css.scss
	-- added style and layout for tags above spectrogram

modified:   app/assets/templates/listen.html
	-- changed tag list on annotation editor form to input[type="hidden"]

modified:   lib/assets/javascripts/jquery.drawabox.js
	-- minor refactor