Travis: test with MariaDB

[grooverdan]

I this added tests for go-1.5 and mariadb.

Unfortunately the default config of 10.0/10.1 is causing failing tests (https://travis-ci.org/grooverdan/mysql-1/builds/76959693) so I needed to lower 1<<25 limit to 1<<23 (24 was still too high).

[julienschmidt]

Error 1118: The size of BLOB/TEXT data inserted in one transaction is greater than 10% of redo log size. Increase the redo log size using innodb_log_file_size

The alternative would be to increase innodb_log_file_size, which I would prefer.

[grooverdan]

fair call. That would require travis-ci/travis-ci/issues/4552 to do it in a container build. I think there is fair grounds for a 50M innodb_log_file_size on travis so that might be a grounds for a setting change in https://github.com/travis-ci/travis-cookbooks/blob/master/ci_environment/mysql/templates/default/my.cnf.erb and https://github.com/travis-ci/travis-cookbooks/blob/master/ci_environment/mysql/templates/default/ramfs/my.cnf.erb.

Any other settings you want changed?

I was thinking of adding an client/server ssl certificate and user ready to use too.

[julienschmidt]

After #560 we are now testing with maria10.1, however it seems like the current default configuration works.

[methane]

I configured max_allowed_packet size on server side in #560.
That's why change in driver_test.go is not needed in #560.

[grooverdan]

Good use of docker and I didn't know you could push so many settings into the matrix section of a travis file. Nice!