Work around bug in colors package when using --no-colors option.

A bug in colors.mode='none' was fixed upstream in:
  https://github.com/Marak/colors.js/commit/5ca667df4a9f86f6c202eca5eb1524cd8d2dd331
but the maintainer of colors has gone AWOL (see
https://github.com/Marak/colors.js/issues/43) and we don't yet have
a released fix.

Work around the bug by manually coercing the results of all naked
color getters to a string.

Change-Id: I4b0559f0dcba766168d13363b771f56b45e3b34c
Merge "Work around bug in colors package when using --no-colors option."