Added opt-out capabilities.

Now contributers will be able to opt out of recieving a reward,
such as when submitting minor typo fixes.

Implemented @moxie0 's request re comments and asterisks in opt-out method

fixed README to reflect lack of asterisks in Opt-out

Addressed @moxie0's request re freebie and parens
Merge pull request #6 from TheBritKnight/master

Added opt-out capabilities.