Add the ability to specify user pillar data in the form of either

  mysql:user:host

  or

  mysql:user:hosts

If mysql:user:hosts is used, an account for each 'user'@'host' combo
will be created with the specified grants

This fixes #49
Merge pull request #55 from vschum/multiple-hosts-per-user

Add the ability to specify user pillar data in the form of either