HUE-1921 [core] Fix IE9 glitches

Removed download graph button
Fixed Spark app
HUE-1911 [core] banner_top_html is escaped

Removed escaping
Added custom banner to login page too
HUE-1882 [core] OAuth support for Facebook, Twitter, Google+ and Linkedin
HUE-1901 [oozie] Add a test for import subworkflow