HUE-1909 [impala] No errors are displayed

In both Impala/Beeswax:
- create table already exists three times
- create aaaaaaa thre times
- one multiple query three times: show tables, create aaaaaa, select * from sample_07
- explaine with good and bad synxtax several times
[beeswax] force scroller to work

Add logic to retry scroller until it resizes.
HUE-1915 [core] MultipleObjectsReturned for tags or permissions

Only a strict unique clause in a DB could prevent duplicate tags or permissions
to be created. We clean them up at access time instead of filing as it is safe
to delete the duplicates.

Strick DB that fails when installing the Hue example should click on each individual
example install insteaf of the install all button.
[core] Improve logging timezone information
HUE-1908 [beeswax] Database of a saved query is not loaded back when opening it

Need specific logic for different states: query history, design, and execute query.
If query history or design, need to wait for databases and design/query to load.
Otherwise, just need to wait for databases to load.