Use a child template to render the gallery if it exists.

Users can now place custom templates at the following paths to override the templates to be used while rendering the Vimeography gallery:

  wp-content/themes/[my_wordpress_theme]/vimeography/[my_vimeography_theme]
  wp-content/themes/[my_wordpress_theme]/vimeography/[my_vimeography_theme]/partials

If the directory does not exist or the template is not found, we'll fall back to the originally intended partial to be loaded.

Closes #8
Update strings in default translation file
Add partial translations for Spanish (90%), German (90%), and Italian (34%)
Do not attempt to enqueue assets if it is an AJAX request
Bump to v1.2.2
Merge branch '1-2-develop'