Reshuffle requirements, and add a document on contributing

.travis.yml

@@ -5,7 +5,7 @@ python:
   #- 3.2
   - 3.3
   - 3.4
-install: pip install -r test-requirements.txt
+install: pip install -r requirements/test.txt
 script:
     - nosetests --with-cov --cover-package=ddt
     - flake8 ddt.py test

CONTRIBUTING.md

@@ -0,0 +1,35 @@
+# Contributing to DDT
+
+We'll be happy if you want to contribute to the improvement of `ddt`.
+
+Code contributions will take the form of pull requests to
+[the github repo](https://github.com/txels/ddt).
+
+Your PRs are more likely to be merged quickly if:
+
+ - They adhere to coding conventions in the repo (PEP8)
+ - They include tests
+
+## Building
+
+
+The simplest way to build `ddt` is using `tox`:
+
+```
+pip install tox
+tox
+```
+
+This will run tests on various releases of python (2 and 3, as long as they
+are installed in your computer), run `flake8` and build the Sphinx
+documentation.
+
+PRs to `ddt` are always built by travis-ci using tox.
+
+Alternatively, if you ony want to run tests on your active version of python,
+I recommend you make yourself a virtual environment and:
+
+```
+pip install -r requirements/build.txt
+./build.sh
+```

requirements/build.txt

@@ -1,2 +1,4 @@
+-r test.txt
+
 Sphinx
 sphinxcontrib-programoutput