Cache tox build on travis to seed up tests

.travis.yml

@@ -16,6 +16,7 @@ env:
 cache:
   directories:
     - $HOME/.pip-cache/
+    - $HOME/build/nitmir/django-cas-server/.tox/
 install:
   - "travis_retry pip install setuptools --upgrade"
   - "pip install tox"

tox.ini

@@ -15,9 +15,11 @@ exclude=migrations
 [base]
 deps =
     -r{toxinidir}/requirements-dev.txt
+passenv=PIP_DOWNLOAD_CACHE
 
 [testenv]
 commands=py.test {posargs:cas_server/tests/}
+passenv={[base]passenv}
 
 [testenv:py27-django17]
 basepython=python2.7
@@ -59,10 +61,13 @@ deps =
 basepython=python
 deps=flake8
 commands=flake8 {toxinidir}/cas_server
+passenv={[base]passenv}
 
 [testenv:coverage]
 basepython=python
-passenv=CODACY_PROJECT_TOKEN
+passenv=
+    CODACY_PROJECT_TOKEN
+    {[base]passenv}
 deps=
     -r{toxinidir}/requirements-dev.txt
     codacy-coverage