Update django-statsd to 7af5cbf9

Changes:

7af5cbf Merge pull request #24 from crankycoder/vng/metlog_prefix
bd9235e * added support to moz_metlog client to support the STATSD_PREFIX in django settings * forced the use of django < 1.5 f
bb60197 bump version to 0.3.8.5
f229781 Merge pull request #21 from youngbob/master
f8d3860 Merge pull request #20 from ConsumerAffairs/master
7f4ee09 Update url imports for Django 1.4+
0b061de don't report 500 for Http404
9ccb0f8 add in gauge support
97f37ea Merge pull request #19 from youngbob/master
ce8c1b8 Implement gauge. Alternate clients now inherit from the null client.
940dab3 Merge pull request #18 from robhudson/formatting
e269ef7 Cleaned up table formatting and padding
d578cf1 bump version with the last two bug fixes
fcf57a3 Merge pull request #17 from tominsam/master
5dc7a6e self-closing divs aren't valid, and this one is trapping the global debug toolbar djDebugWindow view.
fe2de5c Merge pull request #16 from glogiotatidis/master
0934a1f Cope with non Tastypie URLs.
43a8e95 cope with non tastypie urls
163507a add in some tastypie middleware
cca1a3d add in message about the client
79d2534 add in a nose client