[#434] Acceptance tests for mysql_database

Includes a test for the regression fixed in 30ce3e0.

NB: The `ensure => present` on the resource without any `charset` or
`collate` arguments is intentional because of issue described in #458
Merge pull request #459 from dcarley/434-acceptance_tests_for_mysql_database

[#434] Acceptance tests for mysql_database