Fix permanent hostname issue

Chef server can not function properly with incorect hostname.
Docker allows to override hostname on docker run -h <new_hostname> but chef server need to be reconfigured if hostname changed.

This commit introduce changes in startup script that will check current hostname and reconfigure chef-server if hostname changed.
Because deafult hostname empty - startup script will trigger reconfiguration on docker run anyway so doing this during docker build not required any more.

P.S. it was also hanging up on docker build for me, at reconfiguration step.