added methods/tests for facet.query params
Working on Date facets

- slider working
- histogram working
Year facets

- Slider with range and boxes for manual input
  - Implemented using jQuery UI
- Histogram with plot of years
  - Implemented using d3.js and vega.js
- New templates
- New tests
Merge branch 'date_facet'

Conflicts:
	adsabs/static/js/facets_components.js
Some config parameters changed
filter queries need to specify the aqp query parser
response object strips "aqp" query parser

and masks this parameter from the interface
Bug fixes

Fixed bug with disabling click event and bug with the dimension of the
publication year plot.
Small changes to the configuration
Fixed some redirect on user login/logout
Added citation count to api response data
First version of user cookie id

an user cookie id is always available
in the flask g variable.

cookies are bound to the user if logged in
otherwise they are random unique strings

Some tests still missing
Tests for user module
Error management reviewed

- an error coming from SOLR during the search doesn't generate a 500
error in BEER
- an error message is showed together with the search form
- all the custom error pages reviewed
- 500 error page much more explicative (but it should appear only in
case of a real crash in BEER)
- modifications to the request and response objects
- many tests (also for previous methods in the response object)
logging overhaul:

* simplify blueprint config and allow for module setup() method
* add redis logging functionality
* simplified base logging setup to use app.logger
* search module logs data extracted from response to redis
use standard redis port
Multiple improvements in search:

- fixed bug #348:forcing {!aqp} parser for pubdate_sort
  now the field used for date search is pubdate; 
  query syntax changed; tests modified
- search form now produces error message in case of validation error
Few changes for the logging
Icons added
Few changes in the layout