updated the contribution page

Updated with examples of what to submit to the issues page
Updated where mailing list located and use of.
Update with coding style conventions.
Merge branch 'master' of https://github.com/ga4gh/ReadTaskTeam into contribution_documentation
removed the Google Groups mailing list until we have a community friendly one
s/Github/GitHub/g
Merge branch 'master' of https://github.com/ga4gh/ReadTaskTeam into contribution_documentation
typo fix s/test/tests/
Merge branch 'master' of https://github.com/ga4gh/ReadTaskTeam
updated style guide for comments
Updated contribution documentation

Added a section on how issues are resolved.
Cleaned up some of the wording
small change to indent style guide bullets for comments
small edit to section header
Added suggested changes from @dglazer from issue #36

- s/they/the/
- clearer language on contribution methods
- clearer language on vote scheme
s/GA4GH ReadTaskTeam Project/GA4GH Schemas/
Merge pull request #36 from delagoya/contribution_documentation

Contribution documentation