Set up tox.ini to run more properly:

- Don't run dbupdate... the tests themselves do this, and we might
   mess up someone's db
 - We shouldn't run setup.py develop because that installs a new
   *live* db... the tests do isolation, so...
 - Install the package's dependencies by the package itself... it
   seems that removing "skipsdist = True" fixes this
 - Run py.test manually rather than use runtests.sh (which itself uses
   ./bin/py.test if it can)

tox.ini

@@ -1,14 +1,11 @@
 [tox]
 envlist = py27, py33
-skipsdist = True
 usedevelop = True
+sitepackages = False
 
 [testenv]
 whitelist_externals = sh
-commands =
- python setup.py develop
- gmg dbupdate
- sh runtests.sh
+commands = py.test ./mediagoblin/tests --boxed
 deps =
  git+https://github.com/ianare/exif-py.git@develop
  lxml