[TASK] Add Code of Conduct
[TASK] Add Code of Conduct

This adds a reStructuredText version of the Contributor Covenant
code of conduct, to make it clear the project is governed by that.

See also http://contributor-covenant.org/version/1/2/0/

dlubitz/flow-development-collection,aertmann/flow-development-collection,dfeyer/flow-development-collection,kdambekalns/flow-development-collection,neos/flow-development-collection,chewbakartik/flow-development-collection,daniellienert/flow-development-collection,robertlemke/flow-development-collection,daniellienert/flow-development-collection,daniellienert/flow-development-collection,dfeyer/flow-development-collection,kitsunet/flow-development-collection,kdambekalns/flow-development-collection,fcool/flow-development-collection,bwaidelich/flow-development-collection,kitsunet/flow-development-collection,fcool/flow-development-collection,albe/flow-development-collection,mkeitsch/flow-development-collection,robertlemke/flow-development-collection,gerhard-boden/flow-development-collection,chewbakartik/flow-development-collection,fcool/flow-development-collection,dlubitz/flow-development-collection,neos/flow-development-collection,neos/flow-development-collection,aertmann/flow-development-collection,chewbakartik/flow-development-collection,kdambekalns/flow-development-collection,dlubitz/flow-development-collection,bwaidelich/flow-development-collection,mkeitsch/flow-development-collection,aertmann/flow-development-collection,gerhard-boden/flow-development-collection,dfeyer/flow-development-collection,mkeitsch/flow-development-collection,fcool/flow-development-collection,albe/flow-development-collection,neos/flow-development-collection,albe/flow-development-collection,robertlemke/flow-development-collection,kitsunet/flow-development-collection,bwaidelich/flow-development-collection,gerhard-boden/flow-development-collection,kdambekalns/flow-development-collection,robertlemke/flow-development-collection,dfeyer/flow-development-collection