Adding simple get by URI in pages_m model.

Some upcoming additions will make use of this. It allows you to use the 'get by uri' logic without having to get all the entry data and other items associated with a page (i.e., the page type).
Merge branch '2.2/develop' of github.com:pyrocms/pyrocms into 2.2/develop
Bumping migrations to 118.

This is necessary to make #2297 work.