Merge branch 'develop'
Update package.json
Update README.md
Update some parts of Readme
Replace argument building with polymorphism. Add Argument class. Move methods from ArgumentHandler class to Argument class.
Rename ArgumentHandler.build() to .buildString()
Use array.push() instead of string appending in Gremlin.appendCollection(). Update Pipeline.retain() test accordingly.
Remove Argument.isClosure()
More use of array.push()
Fix Pipeline.select() test not passing
Move argumenthandler.js to /arguments
Extract buildArguments() method from ArgumentHandler and move it to ArgumentList class
Remove Argument.handleArray() method
Fix ClosureArgument class
Fix inheritance issue with Object and Closure arguments
Add ArrayArgument class
Rename arg to rawArg
Merge branch 'arguments' into develop
Merge branch 'develop'
Update README