add initial tox support

This adds support for two environments: 'py27' for basic tests, and
'deprecations' to run tests with deprecation warnings turned on (the
latter is meant to be run from a buildbot step that knows how to count
and format the warnings nicely).

.gitignore

@@ -34,3 +34,4 @@ zope.interface-*.egg
 /coverage-html/
 /miscaptures.txt
 /violations.txt
+/.tox/

tox.ini

@@ -0,0 +1,30 @@
+# Tox (http://tox.testrun.org/) is a tool for running tests
+# in multiple virtualenvs. This configuration file will run the
+# test suite on all supported python versions. To use it, "pip install tox"
+# and then run "tox" from this directory.
+
+[tox]
+envlist = py27
+
+[testenv]
+passenv = USERPROFILE HOMEDRIVE HOMEPATH
+commands =
+         # remove this after we move to Versioneer
+         python setup.py update_version
+         # This step should be removed after we get rid of bin/tahoe. It's
+         # currently needed because test_runner.(BinTahoe,RunNode) and part
+         # of test_system.SystemTest depends upon $checkout/bin/tahoe . In
+         # the future, users will just use 'tahoe' from $PATH (which, in the
+         # virtualenv, will be venv/bin/tahoe), and those tests will probably
+         # be deleted.
+         python setup.py make_executable
+         trial --rterrors allmydata
+
+[testenv:deprecations]
+passenv = USERPROFILE HOMEDRIVE HOMEPATH
+setenv =
+         PYTHONWARNINGS=default::DeprecationWarnings
+commands =
+         python setup.py update_version
+         python setup.py make_executable
+         trial --rterrors allmydata