Fix `render file:` deprecation warning (#3454)
Fix `render file:` deprecation warning (#3454)

DEPRECATION WARNING: render file: should be given the absolute path to a file

We were giving it an absolute path, but removing the `.html` so it was causing
a deprecation warning to be shown while running this code.
refinery/refinerycms,anitagraham/refinerycms,anitagraham/refinerycms,refinery/refinerycms,refinery/refinerycms,anitagraham/refinerycms