Add feature support for emulate_model_alias

New method ui_set_model_alias in UIBackstore class is invoked in
the ui_command_create method of each subclass.  The method either
sets the attribute successfully or raises an informational error.
The storage object is created either way.

Signed-off-by: Tregaron Bayly <tbayly@bluehost.com>
Merge pull request #17 from tjbayly/master

Add feature support for emulate_model_alias