bug 839214 - add celery tasks for es indexing

elasticutils tasks broken; add tasks in search app

test
bug 839214 - live indexing into elastic search

Code borrowed in large part from mozilla/fjord

update elasticutils, using pyelasticsearch with updated requests library

update test-utils library to eagerly test celery tasks
update tests for new test-utils
(some) code cleanup
remove obsolete search tests

don't ignore settings_test
new bulk reindex command

remove sphinx modules from search app
waffle search view to ES
disable ES_LIVE_INDEX during tests
fix bug 844528 - no robots on allizom hosts
fix bug 850739 - put events map behind waffle
Merge pull request #927 from groovecoder/events-map-flag-850739

fix bug 850739 - put events map behind waffle
Merge pull request #926 from groovecoder/robots-dev-844528

fix bug 844528 - no robots on allizom hosts
Update installation-vagrant.rst
Merge pull request #928 from groovecoder/master

add link to download xcode command line tools
Improve support for the user's language preferences.
fix bug 841735 - Prevent self-redirecting
Fix ValueError: too many values to unpack.
Fix NameError: global name 'ranked' is not defined.
Merge pull request #929 from darkwing/self-redirect-841735

fix bug 841735 - Prevent self-redirecting
Fix bug 850656: Set based_on field correctly