Disable colorized output from StatusTable unless STDOUT.tty? is true.

I often want to pull hostnames from the output of this class using `grep` and other shell commands for automation. The `colored` gem does not remove formatting when STDOUT is not a TTY, meaning that the hostnames I pull out end up having formatting bytes surrounding them, which I then have to strip out using `sed`.

This PR puts a level of indirection in front of the `colored` methods so that they return the string unmodified for non-TTY output streams.