[webui] continue refactoring the top smells
[api] fix test suite on SLE11

Avoid comparing <comment/> with <comment></comment>

They are equal on all useful meanings, but not if you compare strings
[backend] fix wipepublishedlocked command
[api] cleanup published binaries for released maintenance incidents

unfortunatly no test case because we only have a "noaccess" maintenance test case yet.
[backend] wipepublishedlock: send event to publisher
[backend] send publish event after wiping from repserver directly to publisher

it got send to schedulers which could not handle it
[api] release maintenance updates to public and test published repo wiping
[backend] deliver correct error code 404 for missing published files
[backend] cleanup commit #3cb80b58
[backend] calculate and transfer "base" repo

Gets stored in repoinfo by publisher and is used in published
binary search.
[api] start to move some exceptions to a central place
[api] start to move maintenance logic into API models