Add quote to username and host in mysql_grant constructor

The quote is need for username and host in mysql grant. revoke and grant function is already doing it with cmd_user(). not sure why the constructor didn't do it. This patch fixed #261 and #262.
Merge pull request #263 from xcompass/fix-quote-username-host

Add quote to username and host in mysql_grant constructor
change mysql::server::enabled default to false
change mysql::server::manage_service default to false
Merge branch 'master' of https://github.com/jabox/puppetlabs-mysql