Print help dialog if called without arguments
Print help dialog if called without arguments

Fixes #15

rcorp/vulcanize,Polymer/tools,Polymer/polymer-bundler,Polymer/tools,threeday0905/vulcanize,wprl/spock,bendroid/vulcanize,Polymer/tools,rcorp/vulcanize,Polymer/polymer-bundler,Polymer/tools,threeday0905/vulcanize,Polymer/polymer-bundler,bendroid/vulcanize