Add dev-requirements.txt with a number of tools

MANIFEST.in

@@ -1,5 +1,6 @@
 include *.py
 include *.rst
+include *.txt
 include .coveragerc
 include .mailmap
 include .travis.yml

dev-requirements.txt

@@ -0,0 +1,25 @@
+# Build documentation
+sphinx
+
+# Check code style, errors, etc
+flake8
+flake8-import-order
+
+# Mock dependencies in tests
+mock
+
+# Test runners
+nose
+tox
+
+# Measure test's code coverage
+coverage
+
+# Check that MANIFEST.in matches Git repo contents before making a release
+check-manifest
+
+# To make wheel packages
+wheel
+
+# Securely upload packages to PyPI
+twine

docs/contributing.rst

@@ -35,6 +35,10 @@ Making changes
 
 #. Install dependencies as described in the :ref:`installation` section.
 
+#. Install additional development dependencies::
+
+       pip install -r dev-requirements.txt
+
 #. Checkout a new branch (usually based on ``develop``) and name it accordingly
    to what you intend to do.
 
@@ -82,12 +86,7 @@ Testing
 Mopidy has quite good test coverage, and we would like all new code going into
 Mopidy to come with tests.
 
-#. To run tests, you need a couple of dependencies. They can be installed using
-   ``pip``::
-
-       pip install --upgrade coverage mock nose tox
-
-#. Then, to run all tests, go to the project directory and run::
+#. To run all tests, go to the project directory and run::
 
        nosetests