Revert "In the past I was seeing failures to read when multiple requests came in for the exact same metric  and the locking around the existing conncetions was not adequate."

This reverts commit e37edecafe018761cac3ab353fbca9516b13bbb9.
Implement a config file for the render system.

First config setting is the trimming of most recent datapoints in aggregate functions when some contain nulls.  This prevents the right hand side of graphs from dipping.
Sort series by default so colors are more consistent across graphs
Merge branch 'rfc/render_config' into appnexus_rollup

Conflicts:
	webapp/graphite/render/functions.py