display:__init__: Make display subsystem a module

Add __init__.py to the display subsystem.

Signed-off-by: Guofeng Liu <lgf612@sina.com>
test:test_output: Add new test for colored output

A small demo for how to use PrintColor highlighting some
information. Currently only support Linux host.

Signed-off-by: Guofeng Liu <lgf612@sina.com>
display:output: Remove the code for test

The test for features in output has been moved to the test
subsystem. Remove the test code from output.

Signed-off-by: Guofeng Liu <lgf612@sina.com>