Fix rake {clean,clobber} warnings of phost.
Fix rake {clean,clobber} warnings of openvswitch.
Fix rake {clean,clobber} warnings of oflops.
Fix rake {clean,clobber} warnings of cmockery.
Fix rake {clean,clobber} warnings of vendor/openflow*
Do not clean vendor/openflow with rake clean.
Fix rake {clean,clobber} warnings.
Added contribution guidelines.
fixed notification of connection status to switch-manager
add errno check when delete the pid file