Fix a bug related to method name mismatch
Implement renaming of files
Implement drag and drop in tree
Basic implementation of file move operation
Major refactoring of controller layer

Summary of changes:
- Controller layer does not manipulate the views through their methods
  rather it publishes completion-success events which are intercepted
  by respective views which update themselves accordingly.
- View instances do not manipulate the entity collection but just
  read from it.
- New controller instances are created for every A.initiate call
  and the instances are disposed off once the entire request-response
  handling is over.
- The API of Controller classes remodelled to streamline the code