HUE-1913 [impala] invalidate metadata breaks the editor

Add an empty column list instead of null.
Hide chart and column tabs when no result
(better to hide for no result instead of no columns for now and an empty
query has no results so no results.column)
HUE-207 [beeswax] Leverage tablib to enable more flexible data export from Beeswax
HUE-1826 [impala] Download or export query result

Number of initial rows of a result set to ask Impala to cache in order
to support re-fetching them for downloading them.
Set to -1 for disabling the option and backward compatibility.
HUE-1927 [beeswax] Loading a query history of a saved query does not load its name
HUE-207 [core] upgrade tablib to development version
HUE-1784 [oozie] False positive variable when submit from HDFS

Simple variable names like $var were only valid in Hue 2. It was a Hue
thing, Oozie only supports ${var} parameters.
To be more consistent only the curly bracket form is valid, e.g.: ${var}
Renamed test files to *_tests.py
HUE-1934 [beeswax] Flag for automatic closing the queries

Hue will try to close the Hive query when the user leaves the editor page.
This will free all the query resources in HiveServer2 but also make its results inaccessible.
close_queries=false
[core] logging should be timezone aware for all systems

On ubuntu 12.04, timezone information is missing due to
http://bugs.python.org/issue1493676.

Adding a pytz formatter that is timezone aware.
HUE-1937 [beeswax] Clarify behavior of a multi query with error

When a multi query as an error, the user can modify the query and
click next to try to re-execute it without re-executing the queries
before.
The frontend was changed to transmit the full query each time between
two next statement. We also don't increase the statement number in
case of failure before.
We could also update the query between two statements but are not
doing it.

Fix in Oozie:
A PREP workflow should have the kill option
A coordinator workflow can become non in rare cases
[beeswax] Fix HTML escaping of result table

Check for XSS and NULL display.
Move logic to backend to do it only once and more efficiently.
Merge remote-tracking branch 'remotes/origin/testing' into testing