The sync rendering unit tests now pass.

Updated all the unit tests to get their results from render() in a
callback instead of as a return value. I believe this is an
implementation detail that shouldn't end up exposed to the application
level, but I don't know the code base well enough to be sure yet.

To excute just the template/view system tests, run:
mocha -R spec test/unit/views.js

Fixed bugs exposed in renderSync() by the unit tests.

Added blade to the dev dependencies.