Python 2.6 Compatibility

A string formatting shortcut available in Python 2.7 prevented 2.6
users from running the code. This should be fixed now.
Refactored README.txt as markdown. Renamed to README.md.
Added requirements.txt for pip.
Added pip usage to README to install dependencies.
Added docopt to requirements.txt.
Refactored argument parsing to use docopt.
Made makePlan.py executable.
Moved agent count argument to an option. Default is 1.
Removed redundant check for num of args; docopt takes care of this.