Add contributing info and guidelines

per https://github.com/blog/1184-contributing-guidelines
add a more terse version for folks who arent brand new
Merge pull request #5 from imlucas/contributors

Add contributing info and guidelines
Merge pull request #4 from imlucas/jshint_rules

Add default jshint linting rules
Merge branch 'master' into make-test.js-pass-failing-jshint-80-char-limit