allow registry login without email
allow registry login without email

Since docker 1.13 the email option on login is deprecated
snahelou/garethr-docker,Tradeshift/garethr-docker,HackerHappyHour/hackerhappyhour-docker,bmcbm/garethr-docker,HackerHappyHour/hackerhappyhour-docker,garethr/garethr-docker,snahelou/garethr-docker,SUNET/garethr-docker,snahelou/garethr-docker,SUNET/garethr-docker,bmcbm/garethr-docker,SUNET/garethr-docker,garethr/garethr-docker,Tradeshift/garethr-docker,HackerHappyHour/hackerhappyhour-docker,garethr/garethr-docker,bmcbm/garethr-docker,Tradeshift/garethr-docker