Add head block to base template

Allow apps to extend the head tag further - for instance, the job board app utilises jquery autocomplete which requires a stylesheet and script inclusion.
Merge pull request #410 from joncle/patch-1

Add head block to base template
Use console email backend for local development
Merge pull request #417 from python-jobs-board/console-email-backend-for-local-dev

Use console email backend for local development
Updated UGC fields to enable escaping in MarkupFields.

Thank you to Vinod for reporting.
Merge pull request #421 from python/bugfix/ugc-escape-fields

Updated UGC fields to enable escaping in MarkupFields.
Merge branch 'master' into release