Custom Page Templates

fixes #1969

- creates new ./server/helpers/tempalte.js method
 which returns the correct view to use when rendering

- updates fronted controller to check if a custom page template
 exists and if so then uses that to render the static page

- adds additional class name to body_class helper when
 a custom page template is being rendered

- adds tests to address all new features
Merge pull request #2243 from hswolff/custom-page-templates

Custom Page Templates