Bug 1228335 - Use requests.post()'s json parameter for ES submission
Bug 1228335 - Use requests.post()'s json parameter for ES submission

Requests 2.4.3+ supports a json parameter to `.post()`, which avoids the
need to `jsom.dumps()` the body.

This also removes the unnecessary headers and layers of variables.

glenn124f/treeherder,parkouss/treeherder,wlach/treeherder,avih/treeherder,kapy2010/treeherder,tojonmz/treeherder,parkouss/treeherder,KWierso/treeherder,tojonmz/treeherder,avih/treeherder,glenn124f/treeherder,glenn124f/treeherder,parkouss/treeherder,tojonmz/treeherder,tojon/treeherder,edmorley/treeherder,avih/treeherder,akhileshpillai/treeherder,avih/treeherder,kapy2010/treeherder,glenn124f/treeherder,edmorley/treeherder,KWierso/treeherder,tojonmz/treeherder,tojon/treeherder,kapy2010/treeherder,wlach/treeherder,akhileshpillai/treeherder,parkouss/treeherder,KWierso/treeherder,wlach/treeherder,avih/treeherder,akhileshpillai/treeherder,parkouss/treeherder,glenn124f/treeherder,tojonmz/treeherder,tojon/treeherder,wlach/treeherder,edmorley/treeherder,akhileshpillai/treeherder,edmorley/treeherder,akhileshpillai/treeherder,tojon/treeherder,KWierso/treeherder,wlach/treeherder,wlach/treeherder,avih/treeherder,kapy2010/treeherder,tojonmz/treeherder,parkouss/treeherder,kapy2010/treeherder,akhileshpillai/treeherder,glenn124f/treeherder