shorten connection timeout for http interactions with containers
shorten connection timeout for http interactions with containers

This issue came to light in the context of `weave launch`. When the
weaver container died after we've completed network configuration, it
would take a minute for the script to terminate, due to `curl` being
stuck in a connection attempt.

Fixes #538.

squaremo/weave,awh/weave,weaveworks/weave,awh/weave,n054/weave,OnePaaS/weave,narry/weave,narry/weave,achanda/weave,beni55/weave,bboreham/weave,awanke/weave,tomwilkie/weave,cgvarela/weave,paladin74/weave,BWITS/weave,awh/weave,achanda/weave,BWITS/weave,rade/weave,squaremo/weave,paulbellamy/weave,bboreham/weave,beni55/weave,OnePaaS/weave,squaremo/weave,aaam/weave,philipz/weave,kidaa/weave,paladin74/weave,2opremio/weave,awh/weave,n054/weave,dpw/weave,inercia/weave,errordeveloper/weave,tomwilkie/weave,tomwilkie/weave,beni55/weave,cgvarela/weave,kidaa/weave,achanda/weave,dpw/weave,rade/weave,awh/weave,n054/weave,bboreham/weave,beni55/weave,2opremio/weave,squaremo/weave,paladin74/weave,squaremo/weave,weaveworks/weave,philipz/weave,inercia/weave,narry/weave,inercia/weave,aaam/weave,awanke/weave,philipz/weave,ycaihua/weave,weaveworks/weave,kidaa/weave,BWITS/weave,tomwilkie/weave,OnePaaS/weave,ycaihua/weave,BWITS/weave,cgvarela/weave,achanda/weave,kidaa/weave,rade/weave,dpw/weave,rade/weave,ycaihua/weave,tomwilkie/weave,dpw/weave,BWITS/weave,narry/weave,paladin74/weave,cgvarela/weave,errordeveloper/weave,beni55/weave,achanda/weave,awanke/weave,bboreham/weave,n054/weave,2opremio/weave,philipz/weave,dpw/weave,errordeveloper/weave,cgvarela/weave,OnePaaS/weave,errordeveloper/weave,kidaa/weave,paulbellamy/weave,OnePaaS/weave,rade/weave,inercia/weave,bboreham/weave,aaam/weave,aaam/weave,2opremio/weave,aaam/weave,paladin74/weave,ycaihua/weave,awanke/weave,weaveworks/weave,n054/weave,errordeveloper/weave,awanke/weave,ycaihua/weave,philipz/weave,inercia/weave,paulbellamy/weave,2opremio/weave,narry/weave,paulbellamy/weave