Added drupalgap.loader and changed drupalgap_loading_message_show() to use whatever loader mode is currently set, 'loading' (default) or 'saving'.
Changed _drupalgap_form_submit() to asynchronously process image fields before moving onto the form validation and submission, also removed the drupalgap_goto() call at the end of the form submission mechanism, we are going to leave this up to the form's implementor.
Changed drupalgap_entity_form_submit() to handle the call to drupalgap_goto() since the core form submission mechanism does not take care of that anymore, also added the 'saving' mode for the jQM loader during entity form submission.
Removed _image_field_form_validate(). Changed _image_field_form_process() to use the 'saving' mode for the jQM loader.
Changed drupalgap.settings.loading to drupalgap.settings.loader and added two modes, 'loading' and 'saving'.