Load existing model names when creating versions

Now, versions can be created for models that are defined. Not randomly.
Generic methods to load models and versions

2 methods to load model names and model version using AJAX calls in
versions and queries pages.
Update Query JS

To include AJAX load of model name and model versions on page load
UI change model name and version from textbox

to combobox
Implement call back handler for model name load

AJAX load of model names invokes a call back handler. Implementing a
dummy for that method.
Updated Google App Engine files