Adds Google Analytics demographics tracking code

Google analytics requires a change to the tracking code to enable
demographics tracking.

Also moves the scripts for tracking codes out in to partials so that we
can easily render them only in the production env.
Removes close button from Alpha info alert

As requested. Users can no longer close the alpha info banner.
add S3 polling worker
add whenever scheduling for S3PollingWorker
add new_wdpa? method and refactor S3PollingWorker
add wdpa_import_worker
add test for Wdpa::S3.new_wdpa?
Merge pull request #68 from unepwcmc/alpha-banner-remove-close

Removes close button from Alpha info alert
Merge pull request #67 from unepwcmc/google-analytics-demographics

Adds Google Analytics demographics tracking code
Merge pull request #69 from unepwcmc/add-s3-polling

Add s3 polling
Merge branch 'master' into viz-stats