rpl: mute RPL

Removes all but one occurrence of printf and puts within routing (the
remaining puts is called from a debug function.
add backspace functionality in shell
Add 0x7f as backspace key in shell
Merge pull request #1528 from OlegHahm/silent_rpl

rpl: mute RPL
Merge pull request #1653 from medicalwei/shell_backspace

Add backspace functionality in shell