Use travis user to fix grant issue

This hopefully fixes the following error in travis.
```
Error Trace:	mysql_test.go:93

            				mysql_test.go:35

Error:      	Received unexpected error:

            	Error 1133: Can't find any matching row in the user table

Test:       	TestMysqlTestSuite/TestExample

Messages:   	Unable to grant db permissions
```

.travis.yml

@@ -13,7 +13,7 @@ addons:
 
 env:
   - TEST_POSTGRES="postgres://postgres@localhost:5432?sslmode=disable"
-    TEST_MYSQL="root@tcp(localhost:3306)/"
+    TEST_MYSQL="travis@tcp(localhost:3306)/"
 
 install:
   - mkdir -p $GOPATH/bin