Enable Coveralls (#20)

Maybe? I don't know what I'm doing...

Author: loicteixeira

.travis.yml

@@ -25,6 +25,7 @@ matrix:
      python: 3.6
 install:
 - pip install tox coveralls
+- gem install coveralls-lcov
 script:
 - make test-ci
 after_success:

README.rst

@@ -4,6 +4,8 @@
    :target: https://pypi.python.org/pypi/wagtail-django-recaptcha
 .. image:: https://codeclimate.com/github/springload/wagtail-django-recaptcha/badges/gpa.svg
    :target: https://codeclimate.com/github/springload/wagtail-django-recaptcha
+.. image:: https://coveralls.io/repos/github/springload/wagtail-django-recaptcha/badge.svg?branch=master
+   :target: https://coveralls.io/github/springload/wagtail-django-recaptcha?branch=master
 
 Wagtail ReCaptcha
 =================