Prior to this change, Rocket emitted "white" text in much of its logging
output. On terminals with light backgrounds, the text was nearly
illegible. This PR stops using white coloring altogether, opting instead
to use the terminal's default color albeit with bold styling. On dark
terminals, this will likely be a light color, and on light terminals,
this will likely be a dark color. The end result is that Rocket's
logging output should be readable everywhere.
Resolves#639.