tell travis to run mysql and postgres

sure, we're running both for both all 3 runs
so not perfectly optimal, but greatly simplifies the implementation

Author: kbrock

.travis.yml

@@ -19,6 +19,10 @@ env:
   - DB=mysql
   - DB=postgresql
 
+services:
+  - mysql
+  - postgresql
+
 script: WITH_ADVISORY_LOCK_PREFIX=$TRAVIS_JOB_ID bundle exec rake --trace spec:all
 
 matrix: