tests: update travis.yml for mysql database

- use the travis user instead of root to make the tests pass
  (maybe something has changed since travis is using Trusty as
  default distrib)

.travis.yml

@@ -62,7 +62,7 @@ before_install:
   - "requirements-builder --level=min setup.py > .travis-lowest-requirements.txt"
   - "requirements-builder --level=pypi setup.py > .travis-release-requirements.txt"
   - "requirements-builder --level=dev --req requirements-devel.txt setup.py > .travis-devel-requirements.txt"
-  - "mysql -e 'CREATE DATABASE IF NOT EXISTS travis;' -uroot"
+  - "mysql -e 'CREATE DATABASE IF NOT EXISTS travis; GRANT ALL ON travis.* TO 'travis';' -uroot"
   - "psql -c 'CREATE DATABASE travis;' -U postgres"
 
 install: