add a new autoconfiguration option PRIMARY_HOSTNAME=auto to simply grab the hostname from reverse DNS
add a new autoconfiguration option PRIMARY_HOSTNAME=auto to simply grab the hostname from reverse DNS

drawn from https://github.com/Toilal/mailinabox/commit/5b23a06a7410e4530a56fd6200a6c46c3c6ea9b6.

m4rcs/mailinabox,m4rcs/mailinabox,pierreozoux/mailinabox,jprice/mailinabox,jjz/mailinabox,ianberinger/mailinabox,jjz/mailinabox,m4rcs/mailinabox,jjz/mailinabox,Neopallium/mailinabox,jmedding/mailinabox,jprice/mailinabox,PortableTech/mailinabox,pierreozoux/mailinabox,brocktice/mailinabox,choltha/mailinabox,mail-in-a-box/mailinabox,PortableTech/mailinabox,jjz/mailinabox,b-deng/mailinabox,d5ve/mailinabox,m4rcs/mailinabox,b-deng/mailinabox,jmedding/mailinabox,Neopallium/mailinabox,b-deng/mailinabox,d5ve/mailinabox,d5ve/mailinabox,d5ve/mailinabox,b-deng/mailinabox,brocktice/mailinabox,choltha/mailinabox,mail-in-a-box/mailinabox,PortableTech/mailinabox,ianberinger/mailinabox,Neopallium/mailinabox,Neopallium/mailinabox,ianberinger/mailinabox,jprice/mailinabox,nstanke/mailinabox,brocktice/mailinabox,brocktice/mailinabox,jmedding/mailinabox,pierreozoux/mailinabox,choltha/mailinabox,brocktice/mailinabox,jjz/mailinabox,mail-in-a-box/mailinabox,b-deng/mailinabox,Neopallium/mailinabox,nstanke/mailinabox,nstanke/mailinabox,nstanke/mailinabox,PortableTech/mailinabox,jmedding/mailinabox,PortableTech/mailinabox,choltha/mailinabox,nstanke/mailinabox,mail-in-a-box/mailinabox,jmedding/mailinabox,jprice/mailinabox,d5ve/mailinabox,ianberinger/mailinabox,m4rcs/mailinabox,pierreozoux/mailinabox,pierreozoux/mailinabox,choltha/mailinabox,jprice/mailinabox,ianberinger/mailinabox