Add a dox.yml config file

Dox is a new tool similar to tox but on docker. One of the benefits is
that it eliminates the need of installing all the package dependencies,
which removes the burden from developers.

The tool is still under heavy development but since Zaqar's test suite
is clean and organized, it may be a good project for early adoption.

Change-Id: Iec2698448618fee3019a6877c5c2ae87fda677b6

dox.yml

@@ -0,0 +1,12 @@
+images:
+  - infra/trusty
+add:
+  - requirements.txt
+  - test-requirements.txt
+prep:
+  - apt-get install -y python-dev mongodb-server python-pymongo pkg-config redis-server python-redis libxml2-dev libxslt-dev lib32z1-dev
+  - pip install -U -r requirements.txt -r test-requirements.txt
+  - service mongodb start
+  - service redis-server start
+  - export ZAQAR_TEST_EVERYTHING=1p
+commands: python setup.py testr --slowest