Fix a couple trailing commas in javascript.

A couple small trailing comma errors snuck in since the last time we ran jshint
on all our code. Trivial fix.
Merge branch 'release-2.0.x'
Fix a few more trivial jshint problems.

This fixes a couple variable which were defined but not used, and comments out
an unused argument in an abstract base class. Trivial changes.
Require Python Markdown 2.4.1.

Python Markdown 2.5 was recently released, and doens't support Python
2.6. This broke some users on upgrade. We need to use 2.4.1 instead.
Merge branch 'release-2.0.x'