Changed _drupalgap_form_render_element() to place a hidden input element for images and changed the 'Add image' button's id so it doesn't collide with the hidden input element id. Changed _image_field_form_validate() to skip images that already have a file id set and changed the success callback to set the new hidden input element value with the newly created image file id.
Merge branch '7.x-1.x-alpha' of github.com:signalpoint/DrupalGap into 7.x-1.x-alpha