Add Endpoint.version for hot upgrades
Add Endpoint.version for hot upgrades

As per https://github.com/bitwalker/exrm/issues/206,
setting the Endpoint.version will trigger code_change during hot upgrade
which will in turn reload the asset manifest.

keathley/phoenix,mobileoverlord/phoenix,Joe-noh/phoenix,phoenixframework/phoenix,mschae/phoenix,bsmr-erlang/phoenix,stevedomin/phoenix,mschae/phoenix,mitchellhenke/phoenix,michalmuskala/phoenix,eksperimental/phoenix,rafbgarcia/phoenix,rafbgarcia/phoenix,phoenixframework/phoenix,dmarkow/phoenix,0x00evil/phoenix,0x00evil/phoenix,bratsche/phoenix_guides,eksperimental/phoenix,rafbgarcia/phoenix,phoenixframework/phoenix,0x00evil/phoenix,bsmr-erlang/phoenix,korobkov/phoenix,Gazler/phoenix,Gazler/phoenix,keathley/phoenix,jwarwick/phoenix,michalmuskala/phoenix,nshafer/phoenix,optikfluffel/phoenix,Kosmas/phoenix,trarbr/phoenix,optikfluffel/phoenix,Joe-noh/phoenix,trarbr/phoenix,stevedomin/phoenix,mitchellhenke/phoenix,jwarwick/phoenix,pap/phoenix,gjaldon/phoenix,Kosmas/phoenix,gjaldon/phoenix,mobileoverlord/phoenix,wsmoak/phoenix_guides,evax/phoenix,evax/phoenix,nshafer/phoenix,optikfluffel/phoenix,korobkov/phoenix,nshafer/phoenix,pap/phoenix,dmarkow/phoenix