init_host_server: correct getopts process

Sorry, #85 caused bug variable assignment went long, `PREVIEW_TARGET_URL="pool.dev"`
I fixed this problem. Please check the procedure `vegrant destroy -f && vagrant up` .
@ainoya The problem which caused order-gap of parameters is came from `shift` is called  twice in a loop right?

ex) When `vagrant up` was executed then finished building,  `/app/images/preview-target-repository` has string `pool.dev`