update httpserver
fix warnings
Do not use relative paths in 'run { path ... }'
Do not use '0xe' prefix for switches' dpid
Add flow-dumper.rb
Add slicebale switch sample configurations for the Trema book
Fix bugs of flow-dumper.rb
Modify flow-dumper.rb
Add a timeout method into flow-dumper.rb
Initial Commit
Modify Makefiles for trema installed as rubygems