Initial commit for proposed CONTRIBUTING doc

This commit includes the proposition that we will be using Git Flow as
our Git workflow procedure.

HYDRASIR-62 #start Working document regarding

JIRA References:
https://jira.duraspace.org/browse/HYDRASIR-62
Adding contributor notes for commit messages

Explaining that you can transition stories via commit messages.

HYDRASIR-62

JIRA References:
https://jira.duraspace.org/browse/HYDRASIR-62
Fleshing out Reviewer/Submitter responsibilities

HYDRASIR-62 #close Fleshing out Reviewer/Submitter responsibilities

[skip ci]

JIRA References:
https://jira.duraspace.org/browse/HYDRASIR-62
Adding possible gotchas
Fixing typo

[ci skip][log skip]

JIRA References:
https://jira.duraspace.org/browse/HYDRASIR-62
Merge pull request #384 from projecthydra/HYDRASIR-62-contributing

Changing Contributing document to reflect process