Permit specifying custom host

[farmdawgnation]

My Perl is very rusty so this should be taken with a strong grain of salt. I've not tested it as of yet.

I'm running a MySQL server that for $REASONS has its unix socket inaccessible to the Linode agent. However, whenever you provide the string localhost to a MySQL client library, it's always going to go for the unix socket. My intent with this change is to permit me to provide host 127.0.0.1 so it'll connect over the TCP socket that's open.

[displague]

Relates to https://github.com/linode/longview/pull/6 and #17

[farmdawgnation]

Any movement here?

[farmdawgnation]