Merge pull request #62 from m-abs/master

Filter functions didn't handle undefined values very well.
Add version number to twig.js (#59) Bump version to 0.5.5
Add AMD module definition
Addresses #63 - Add spaceless tag and test.
Bump version to 0.5.6, update 2012 to 2013.
Add (simple) {% raw %} implementation...
Merge pull request #69 from m0ppers/raw

Add (simple) {% raw %} implementation...