add full support for ANSI SGR escape sequences

This is for adding color to the text output salt emits in various
contexts including support for extended colors (256 and 256^3) and a few
other common text modifiers like bold, italic, underline, etc.

The code is put in salt/textformat.py (rather than
salt/utils/textformat.py) in order to allow for logging to import
TextFormat without loading all of salt/utils/__init__.py and causing
logging failures.
finally remove global, unused color declarations
update color name consistency
add color to console logger