Use numpy median function.

Conflicts:
	vizgrimoire/SCR.py
Fix SQL for time diffs. Convert to TIMESTAMPDIFF so the resolution is until microsecs and no prob with max hours limit #2722.
Add support for converting from Decimal to float an array also.
More robust median logic after Wikimedia tests.

Conflicts:
	vizGrimoireJS/scr-analysis.py
	vizgrimoire/SCR.py
Check sql results are array in median query.
Fix error getting top closers by companies and domains

The queries returned an invalid top of closers. Both total count
of closed tickets and their closers were wrong. There was a typo
in the queries that generated the error.
Fixed corner cases: just one repo or just one revision.

Conflicts:
	vizgrimoire/SCR.py
Merge branch 'master' into mediawiki

Conflicts:
	vizgrimoire/SCR.py