+ Reimplement colorized output for logging.
+ Applying to context output.
+ Improve comment.
+ Add global turn color on/off option.
+ Make logging conf file somewhat configurable.
Merge remote-tracking branch 'mark/logging_in_color' into testing_1

Conflicts:
	src/rez/config.py
	src/rez/resolved_context.py
	src/rez/rezconfig
	src/rez/util.py
-updated mark's colorize PR
-fixed bugs wrt signal handling
-turned all debug output into debug logging output