MINOR: cli: allow the semi-colon to be escaped on the CLI

MINOR: cli: allow the semi-colon to be escaped on the CLI

Today I was working on an auto-update script for some ACLs, and found
that I couldn't load ACL entries with a semi-colon in them no matter
how I tried to escape it.

As such, I wrote this patch (this one is for 1.7dev, but it applies to
1.5 the same with just line numbers changed), which seems to allow me
to execute a command such as "add acl /etc/foo.lst foo\;bar" over the
socket. It's worth noting that stats_sock_parse_request() already uses
the backslash to escape spaces in words so it makes sense to use it as
well to escape the semi-colon.