HUE-1785 [oozie] New graph CSS messes up menu labels

Fixed workflow css
[proxy] Proxy app doesn't work if blacklist is empty

Add better default and change empty strings to not be included.
HUE-1722 [impala] Scrolling below initial 100 records shows NULLs as blank values

Loop over cell values to ensure that each null value is represented as the string NULL.
HUE-1787 [sqoop2] python 2.4 json encoding issues
Merge remote-tracking branch 'upstream/master' into testing-abe