HUE-1986 [search] Facets including multibyte chars doesn't work

Added support for UTF-8 facets
HUE-1904 [core] Friendlier login page

Eased proportions
Got rid of labels
The page is using the common_header now
Added global tour to our blog
HUE-1990 [impala] Should not be able to download results for explain queries

Downloading or saving to HDFS/Hive shouldn't be allowed for query explanations.
Add a check for this.
Also, check to see if there are logs when resizing (none when explaining a query).
[core] Hide some ini properties

Mark some properties as private
Even if the private properties are shown, escape the passwords
HUE-1983 [beeswax] Download result as CSV is timeouting

Smaller fetch size
[impala] Improve result fetching status
[impala] Fix backward compatibility with no start_over support

Add some padding in navigator as the scroll bar hides the icon.
HUE-1992 [core] set username to lowercase when using RemoteUserDjangoBackend
HUE-1811 [search] Sample collections

Create 3 examples of collections with several facets and features:
- twitter
- yelp
- log search

The index page of the collections works even without a valid solr for demo purpose.
The collections are moved from the search dropdown to the main menu bar.
Some sample data is available for filling a reald index. Some basic indexing scripts
are in progress in order to offer a good quick start experience.

We are using hardoced ids in the fixtures to keep it simple.

Todo:
- click on install examples installs the example
- add more data and finish the indexing scripts
- collection level permissions
- alert message when using a demo collection without a valid solr
HUE-1811 [search] Alert message when using a demo collection without a valid Solr
HUE-1811 [search] Install examples button in quick start wizard

Also display a landing page when no collections are setup
HUE-1811 [search] Add script for creating the Solr collections

Renamed the example collection to *_demo
[search] Adding sample icons
[search] Integrating icons for demo collections