Use tox to run tests

tox makes testing extremely easy, see <https://tox.readthedocs.org/en/latest/>
for more details.

Converted .travis.yml to use it.

Author: legoktm

.travis.yml

@@ -1,4 +1,4 @@
 language: python
 python: "2.7"
-install: pip install jsonschema
-script: bin/jsonschema_suite check
+install: pip install tox
+script: tox

README.md

@@ -133,5 +133,5 @@ Contributing
 If you see something missing or incorrect, a pull request is most welcome!
 
 There are some sanity checks in place for testing the test suite. You can run
-them with `bin/jsonschema_suite check`. They will be run automatically by
+them with `bin/jsonschema_suite check` or `tox`. They will be run automatically by
 [Travis CI](https://travis-ci.org/) as well.

tox.ini

@@ -0,0 +1,8 @@
+[tox]
+minversion = 1.6
+skipsdist = True
+envlist = py27
+
+[testenv]
+commands = python bin/jsonschema_suite check
+deps = jsonschema