Remove colors.js and replace it with chalk.

[AaronAsAChimp]

This should improve the performance issues reported in Issue #98.

The results of using time bin/blessc chunk ./test/input --out-dir test/output

Before:

real 0m39.666s user 0m39.014s sys 0m0.171s

After:

real 0m14.288s user 0m8.230s sys 0m0.119s

[mtscout6]

Nice! 👍