Holland monitor fails if root's my.cnf is changed

[rillip3]

By default, /root/.my.cnf is used as the credentials for the mysql ping that Holland monitoring performs. This means if a user changes the root password, monitoring fails, even though Holland may still run without issue.

In discussing how this might best be fixed, the two ideas where to simplify the ping check (and not pass the --defaults-file at all, just the Holland user/pass) or to remove the check and use https://github.com/racker/rackspace-monitoring-agent-plugins-contrib/blob/master/mysql_ping.py to monitor MySQL in real time instead of trying to do everything in the one plugin.

[rphillips]

@mckraken thoughts? I reverted #84 for now. Let's get some consensus before we merge it in.

[rillip3]

I had already posted my thoughts on #84 but I can repost them back here if we want to continue the discussion here