Merge pull request #214 from marsqing/master

for hua to sync
Merge pull request #215 from marsqing/master

add default repo file
support tuangou f5 rule
preserve original host in new url
ensure target_pool is not null
add virtual server logic
Merge pull request #217 from leoliang/master

add virtual server support
add original virtual server to cookie
Merge branch 'master' of github.com:dianping/phoenix
support tuangou