Merge pull request #32 from mikeford1/master

hull tech
Added Mike Ford's changes to Hull Slots in template_tech.py & planetNameFromFile from template.py.
Merge branch 'master' of https://github.com/jurlaub/StarsCoreEngine
Added a Contributors file for documenting contributors to the project.
Updated tech.py Hull().slot objectType : value to be a list. This allows for a slot to allow  multiple itemTypes.
Revised comments around a few methods to add to clarity.
Updated Colony growthRate and made associated changes for clarity.
renamed a few variables in the hull slots dicts to aid easier parsing, and change mine to minelayer for clarity