Update .travis.yml

Added coveralls coverage...

.travis.yml

@@ -42,12 +42,17 @@ install:
     - if [[ $DJANGO == 'dev' ]]; then travis_retry pip install https://www.djangoproject.com/download/1.7c2/tarball/; fi
     - if [[ $DJANGO != 'dev' ]]; then travis_retry pip install Django==$DJANGO; fi
     - travis_retry pip install https://pypi.python.org/packages/source/p/python-dateutil/python-dateutil-2.1.tar.gz#md5=1534bb15cf311f07afaa3aacba1c028b
+    - travis_retry pip install coveralls
     - travis_retry python setup.py install
 
 script:
     - travis_retry python setup.py test
     - if [[ $TRAVIS_PYTHON_VERSION == '3.'* ]]; then 2to3 . -w; fi;
+    - coverage run --source=mongoengine setup.py test
+    - coverage report -m
     - python benchmark.py
+after_script:
+  coveralls --verbose
 notifications:
   irc: "irc.freenode.org#mongoengine"
 branches: