Fixed #776 - the output wasn't getting rendered once the procesor was ready.

In addition, it was returning too early, and the `ready` function wasn't called, which meant the processor selection wasn't made.
Preprocessor fixes, and bump LESS to latest

- Fixed #693 and fixed #712 - running with 1.4.2
- Fixed #713 - cmMode for .less is 'less' (not .css)
Fix #799. Throw exceptions & warn of processor fail
Merge pull request #809 from remy/fix/processors-776

Preprocessor fixes