[minor] Add colors options to prompt.start
[minor] Add colors options to prompt.start

This option defaults to `false`, and enables/diables a default set of
colors for the prompts and log messages.

Previously we were forcing grey colors upon users, which was somewhat
opinionated.

Signed-off-by: Tim Smart <5ee0edb9e2229c0838f1959779f1949031de0123@fostle.com>
Signed-off-by: Pavan Kumar Sunkara <1b5e356bb84465e3deee937143bf6a83a050649c@gmail.com>

flatiron/prompt,Icenium/prompt,PFTW/Kerrit,gangstead/prompt,djchie/prompt