Added weave ps command
Fix issues raised in code review
Make extra container information optional
Removed weave ps -v option
Merge branch 'master' into 138_weave_ps

Conflicts:
	weave
Add mac address to weave ps output
CONTAINER_IFNAME rather than ethwe
Inline weave ps function
cosmetic
Add weave ps to usage
cosmetic
Merge pull request #147 from bboreham/138_weave_ps

Add command `weave ps`