Merge branch 'master' into develop
Rewrite some model methods to use Gremlin queries
Move Groovy related class to /groovy folder
Custom groovy functions now accept parameters

- Refactor GroovyParser, add GroovyScript and GroovyFunction classes
- Rename request* methods to execute* in Rexster client
Minor changes in ModelCompiler (renaming, comments, etc.)
Merge branch 'develop'
Update doc
Bump to v0.2.1