WIP Commit.

Minimum working dataflow - query to results.
Only fretext or foreignkey fields, only exact, only one query param.
Merge branch 'master' into extract
Merge branch 'master' into extract
Improvements to extract searching & results presentation.
Initial dummy version of serialisation.
Add helpers to extract fields
Update extract page to add save search button.

refs openhealthcare/elcid#80