* improve TestServer* reliability
* improve TestService_UserReplies reliability
* increase timeout for Test_Main
* improve TestRest_CreateWithPictures readability and reliability
* introduce random port to REST over SSL tests
* tinker TestRest_InfoStreamSince to have more slack before failure
* finalize test errors check unification
* simplify prepServerApp in cmd package tests
* improve TestRest_InfoStreamCancel reliability
* move email unsubscription page outside of API and make it HTML
* make separate HTML template for SendErrorHTML
* fix error template name
* add test for SendErrorHTML, introduce MustExecute function
* fix content check in test of TestSendErrorHTML
* fix logging test to be more generic and not depend on line numbers
* make tests more resilient
* adjust drone for v1.x and dev-box, remove travis support
* add backend build step on branch for drone
* fix from email
* change notif email
* less demanding test wait
* add settings section to drone plugins
* adjust branch build
* convert all drone ci docker confs
* rename drone targets