[webui] avoid visiting / for every login in a test

and other tweaks for the webui test suite - merging all test suites into
one travis job
[api] test and fix release_request creation for channel packages
[api] support channel specific update info templates
[webui] work on the easy targets for incidents table
[api] small refactor of expand_packages method when creating a request
[api] split release_package into logical parts