More detailed "develop" guidelines

[jvanasco]

It would be nice to extend http://www.sqlalchemy.org/develop.html with a few things to further help contributions:

• Preferred method of submissions:
  bitbucket vs github develop on master/branch or create a release/issue branch. if release/issue, is there a preferred naming convention? ** should the fix be based on the branch on master, a release, etc

• should a fix be backported? are there any critera for this? if so, are there any guidelines?

• Is there anything that the package maintainers would prefer in terms of workflow or style that is not covered by the above or the existing guidelines

[Mike Bayer]

do we need to open up sqlalchemyorg to pull requests?

[Mike Bayer]

okey doke let's just do these over at https://bitbucket.org/zzzeek/sqlalchemyorg/issue/1/more-detailed-develop-guidelines