tox: clean up, install with [dev]

tox.ini

@@ -7,21 +7,11 @@
 envlist = {py27,py33,py34,py35,py36,pypy}
 skip_missing_interpreters = True
 
-# On windows we need "pypiwin32" installed. It's supposedly possible to make
-# Twisted do this by depending upon "twisted[windows]" instead of just
-# "twisted", but when I try this via Appveyor, the extra is ignored.
-#    git+https://github.com/twisted/twisted#egg=twisted{env:TWISTED_EXTRAS:}
-#    #twisted{env:TWISTED_EXTRAS:}
-# So instead we have the .appveyor.yml set EXTRA_DEPENDENCY=pypiwin32. In
-# other environments, this variable will be empty, and tox will ignore the
-# blank value.
-
 [testenv]
+skip_install = True
 deps =
+    --editable=.[dev]
     pyflakes >= 1.2.3
-    mock
-usedevelop=true
-install_command = pip install {packages}
 commands =
     pyflakes setup.py src
     wormhole --version
@@ -30,18 +20,17 @@ commands =
 
 # on windows, trial is installed as venv/bin/trial.py, not .exe, but (at
 # least appveyor) adds .PY to $PATHEXT. So "trial wormhole" might work on
-# windows, and certainly does on unix. To get "coverage run" to work, we need
-# a script name (since "python -m twisted.scripts.trial" doesn't have a 'if
-# __name__ == "__main__": run()' -style clause). The script name will vary on
-# the platform.
+# windows, and certainly does on unix. But to get "coverage run" to work, we
+# need a script name (since "python -m twisted.scripts.trial" doesn't have a
+# 'if __name__ == "__main__": run()' -style clause), and the script name will
+# vary on the platform. So we added a small class (wormhole.test.run_trial)
+# that does the right import for us.
 
 [testenv:coverage]
 deps =
+    --editable=.[dev]
     pyflakes >= 1.2.3
-    mock
     coverage
-usedevelop=true
-install_command = pip install {packages}
 commands =
     pyflakes setup.py src
     wormhole --version