add --github-endpoint to login command
bump up gh dependency
load github api endpoint from travis
include github api host in interactive login outpu
Revert "add --github-endpoint to login command"

This reverts commit e73d904d3adea0de8df52d750763e6cea49a9dcb.
travis endpoint --github
update changes
wording, thanks @nschonni
Merge pull request #81 from travis-ci/ghe

add support for different github endpoints