Issue #2913864 by Jo Fitzgerald, chiranjeeb2410, matslats, phenaproxima: badly constructred link in drupal_set_message

Issue #2701541 by xjm, yoroy, catch, mikeryan, Gábor Hojtsy: Rename Drupal Upgrade UI to Migrate Drupal UI

Issue #2281691 by xjm, mikeryan, Gábor Hojtsy, alexpott, tim.plunkett, webchick, abhishek-anand, quietone, yoroy, stevepurkiss, benjy, Bojhan, Ryan Weal, aleksip, anavarre, hussainweb, er.pushpinderrana, cilefen, Luukyb, Jo Fitzgerald: User interface for migration-based upgrades