add/remove program pid file
refactor code to ruby2.0
fix segfault when switch received packet-out with drop action

When the packet-out action was "drop" i.e, empty actions,
"actions" argument passed to handle_packet_out will be NULL.
Merge pull request #30 from iHiroakiKawai/switch_packet_out_drop

fix segfault when switch received packet-out with drop action
Fix broken .feature of learning-switch.
Merge branch 'master' of https://github.com/trema/trema-edge

Conflicts:
	ruby/trema/trema-switch.rb
fix issue#31 add instructions into multipart flow stats reply
fix issue#32 add ruby echo reply handler
send multipart reply in case flow entry was empty

Fixes the problem that switch does not send multipart
reply and keep silent when no flow entry was found.
Merge branch 'multipart_flow_empty_reply' of https://github.com/iHiroakiKawai/trema-edge into multipart_flow_empty_reply