add new app for executing command from BS on mote
add example for rebooting mote remotely
add feature SF_FEATURE_SHELL_OPT in project_conf.h. This allows us to turn on/off shell feature at compiling time
add remote-shell function for handling sending command and command input
modify remote_shell_input() to read packetbuf directly
verify with txpower command. currently able to support command with parameter
enable blink,node_id,txpower,rfchannel
command
add new command: sendcmd. it allows to send command to remote note via serial shell
add msg for incorrect remote shell command. Verified by test
add comments for setting packet cmd attr
resync to dev branch
revise some files to fix incorrect merge
clean code for merge
Merge pull request #25 from s3lsensor/yzliao_v0.2_cmd

Enable command for serial shell and remote shell