Make gitlab url option more comprehensible, https://twitter.com/say_hello_je/status/422534393232912384 didn't get it.
Making it even more similar to the simple server setup of the common user based on https://twitter.com/say_hello_je/status/422652167716364288.
Merge branch 'allowed-urls'

Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>

Conflicts:
	config/application.yml.example
	spec/support/stub_gitlab_calls.rb
Compatibility with old configs

Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>