[core] Small UX fixes

Fail silently on JT error
Changed jHueTour modal text
[jobbrowser] Refactor and fix tests

Submitting only one job if possible and rely on this.
This should simplify the tests.
Refactor and moved to skiptest some parts that fail.
Some parts cold be moved to the mocked part.
[sqoop] Improve testing to show real error
[sqoop] Fix sqoop tests to work with upcoming sqoop 1.99.3 release
[oozie] Fix submittion tests
[oozie] Fix permission tests
[oozie] Get import workflow working again
HUE-1604 [oozie] Jar path in mapreduce action and java action should use File arg
HUE-1594 [core] Revamp login page

Added navigator bar and bottom bar
[oozie] Fix import workflow tests
[hadoop] Set MR2 as default

Keep backward compatibility by not switching current installations to MR2.
[core] Fix add a tag
[oozie] Fix workflow with jar file tests