Add logging feature to SUSI Linux

[hongquan]

SUSI Linux currently lacks logging, which make difficult to debug.

My plan is:

• Add v option to command line, to increase "verbosity" when needed. For example, calling python -m main -v will make SUSI Linux throw more log messages.
• There are 3 levels of log. The level 0 (no v option) is to run SUSI in "production" mode, only error, warning messages are shown. The level 1 (-v) is to show additional info messages, level 2 (-vv) is to show additional debug message. The categories warning, info, debug follows Python's standard logging library.
• The development mode (with -v option) is for developer (human), so we will show color to help read easier.