Instantiate a default Client in the WSGI middleware

Makes client optional. If left off, initialize the default Client()
Merge pull request #285 from mattrobenolt/patch-1

Instantiate a default Client in the WSGI middleware
Remove checksums
Merge pull request #284 from linovia/getsentry_master

Initial Python 3 support
Fix failing tests
Add 3.2 and 3.3 to travis
bootstrap in test
use py.test's skipif
Correct formatting for Python 2.6 compat
Change test to test context (context manager)
Correct django serialization tests
Remove raise
Dont use .format()