Include external_id in admin reports search.

Fixes #389
Add a test for the external_id admin report search
One more external id-related test
change email sender to handle multiple emails per contact

splits emails on comma
WIP
Merge branch '389-report-search-ref' of https://github.com/andylolz/fixmystreet into andylolz-389-report-search-ref
Tests for contact with comma seperated multiple emails
Merge branch 'multiple_emails_per_contact'
remove FixMindelo header, override title instead

The staging banner didn't fit, and .wrapper{position:relative} was breaking things :-(
Easier to keep it simple, drop the header and just set the title in the Cobrand module instead.
[Oxfordshire] Fix map center offset

This fixes the map so the centre is offset to the right to account for
the overlayed sidebar on the left.
Create a single field
Add Jquery-ui files, and fixmystreet-admin.js
Create a single date fields and parse as DD/MM/YYYY
Remove trailing whitespace
Add placeholder text
use local jquery ui, not CDN, for admin datepicker
fix typo and localise placeholders
Merge remote branch 'origin/ab_date'
Make sure admin start is specified for all the static files.
Use relative URLs in case being included via proxy.
Show a graphic on links to non-admin pages

Graphic and css from FMT. Fixes #579.