Add a sample gear-placement plugin

Add a sample gear-placement plugin from abhgupta to use as a template.
Merge pull request #430 from calfonso/master

Add a sample gear-placement plugin
Documentation and Examples for gear placement custom algorithms
Merge pull request #434 from calfonso/master

Documentation and Examples for gear placement custom algorithms
Merge pull request #436 from nhr/master

Fixed answer-checking logic for ruby 1.8.7