Add unit tests for pattern_engines.js and individual pattern engines
Add unit tests for pattern_engines.js and individual pattern engines

pattern-lab/patternlab-node,pattern-lab/patternlab-node,pattern-lab/patternlab-node,pattern-lab/patternlab-node,pattern-lab/patternengine-node-mustache,geoffp/patternlab-node,geoffp/patternlab-node,stevemartin/patternlab-node,stevemartin/patternlab-node