add some fields to models - flagged, hidden, exemplar, created.
get tree by tag number
a whole load of tree view page stuff - flagging things and emailing people. probably need celery?
some simple tests for tree view
requirements for webtest
pep8 fixes
now logging sql queries
Merge branch 'feature/tree-view-page' into feature/my-tags
Adding django-tz-detect for timezone detection
Work on my-tags page