Downgrade colorize from 0.6.0 -> 0.5.8

This dependency was upgraded in 431ce29 with the thought that there were
no breaking changes.

It turns out that it actually removed the automatic disabling of
colorization when the terminal was not a TTY. This resulted in
`scss-lint` printing color escape sequences even when it was being
output to a file.

This is obviously not ideal. Since there are no significant reasons to
upgrade to 0.6.0, downgrade back down to 0.5.8.

Change-Id: If92d7b9ae9c3a11697c1ae833ddc31cfcc328e62
Reviewed-on: https://gerrit.causes.com/33122
Tested-by: jenkins <jenkins@causes.com>
Reviewed-by: Shane da Silva <shane@causes.com>