Use standardized make commands for mysql and postgres

.travis.yml

@@ -10,9 +10,7 @@ before_script:
   - mysql -e 'create database sentry;'
   - psql -c 'create database sentry;' -U postgres
 install:
-  - pip install mysql-python
-  - pip install psycopg2
-  - make develop
+  - make develop dev-postgres dev-mysql
 script:
   - make test
 notifications: