Adding functionality to Command for setting requirements on options
Adding "requires" handling to Option for defining other options that must be set
Adding tests for new "required" handling to Command class
adding tests for new "requires" handling in options
updating from "requires" to "dependsOn" for dependency handling
moving "dependsOn" over to "needs" as per Issue #31
Moving from "dependsOn" to "needs" on Option (Issue #31)
Merge pull request #31 from enygma/add-requires

Add requires