Register commands to the controller class Lshal to autogenerate
help messages and select the correct Command.
Test: lshal_test
Change-Id: I846aef13d77bcee328c8410dc61f2e8b4c0e0d69
Add *Command::usage() function for each Command and let
Lshal class to call them.
Suppress output from getopt_long and write our own
error message to customized error stream (for testing).
Test: lshal_test
Test: lshal --help
Change-Id: I8f5847c84a3e01af29fa85871479cab3baeb5312