Add Travis PyPI release -> RocketChat notifications

Author: ulope

.release_notify.sh

@@ -1,3 +1,6 @@
 #!/usr/bin/env sh
 PAYLOAD="{\"text\": \"<https://pypi.python.org/pypi/ethereum|ethereum $TRAVIS_TAG> was released on pypi!\"}"
 curl -s -X POST --data-urlencode "payload=$PAYLOAD" $SLACK_WEBHOOK_URL
+
+PAYLOAD="{\"text\": \"[ethereum $TRAVIS_TAG](https://pypi.org/project/ethereum) was released on PyPI!\"}"
+curl -s -X POST --data-urlencode "payload=$PAYLOAD" $ROCKETCHAT_URL

.travis.yml

@@ -14,6 +14,7 @@ env:
   global:
     - COVERAGE_APPEND="--append"
     - secure: cKbIgpTJ1yjKLBxpCEiT6IH7NShDWZUE+BvnrAfc+ujCsR6LyLJcKxFQmKnWryJCqg7fp82Ep2bF2oDKzanAROar2xDY1SFGbai42seYMaFCw53YPGJ6u3VNCcfT0rN9BWgE7el/m4fjcD6CRsZYKArNNJbMX8csRt3uXXCFLso=
+    - secure: "Gj9H2vW9ifusxbKLt8mT2G47ExewU9XFcRHDvULfn2hHhJH5cz0kOnW4I5W0EPAits0BRPZJClZV0PgDuo+zDjtEMrhDQYEmvb4KE5euLIm1xmQSkXYhErKxxSdIXSujiJbz4TT/V3FTtpmJWDaSzfwPy2PTK5bjbS+U3h3AlG4="
 install:
   - travis_retry pip install setuptools --upgrade
   - travis_retry pip install tox