Dashboard layout modifications

Dashboard layout modifications
Closes #51 

Upgraded jquery to 1.9.1
Added jquery.shapeshift, (with jquery-ui, jquery-touch-punch dependencies), jquery.flot plugins.
 
The layout mechanism for dashboard widgets has been modified heavily, with the following changes
The  shapeshift plugin is used for layout
rockstor_widgets.js has been added as a widget registry. All widgets must have a corresponding entry in this file.
Dashboard widgets now extend from the RockStorWidget base class.
The home renderWidgets method has been modified to use the shapeshift plugin for layout.

The cpu usage widget has been modified to use the jquery.flot plugin for graphs.