Simplify Travis test matrix

- do not test against Git versions as they are quite often broken so
  this does not add any real value to us
- do not try Python 3 as many of our dependencies are nowehere near
  Python 3 support
Signed-off-by: Michal Čihař <michal@cihar.com>

.travis.yml

@@ -20,20 +20,9 @@ env:
     - CI_PIP_DEPS="Django>=1.7,<1.8"
     - CI_PIP_DEPS="Django>=1.8,<1.9"
     - CI_PIP_DEPS="Django>=1.8,<1.9" CI_DATABASE=postgresql CI_RUN_TESTS="-p test_selenium.py" CI_SELENIUM=1
-    - CI_PIP_DEPS="git+git://github.com/django/django.git git+git://github.com/omab/python-social-auth.git"
-    - CI_PIP_DEPS="https://github.com/translate/translate/zipball/master"
   global:
     - DJANGO_SETTINGS_MODULE=weblate.settings_test
     - CI_REQUIREMENTS=travis
-matrix:
-  allow_failures:
-    - python: "2.7"
-      env: CI_PIP_DEPS="git+git://github.com/django/django.git git+git://github.com/omab/python-social-auth.git"
-    - python: "2.7"
-      env: CI_PIP_DEPS="https://github.com/translate/translate/zipball/master"
-    - python: "3.3"
-  include:
-    - python: "3.3"
 # commands to install dependencies
 install:
   - ./ci/install