dvc: logger: use colorama to colorize output

Colors help readability, especially in verbose mode.
Current color map:

	Debug:   Blue
	Info:    White
	Warning: Yellow
	Error:   Red

setup.py

@@ -90,6 +90,7 @@ install_requires = [
     'six==1.10.0',
     'traitlets==4.3.2',
     'wcwidth==0.1.7',
+    'colorama',
 ]
 
 if platform.system() == 'Darwin':