more detailed failure report on job end

list test failures (if found) or the tail of the log

auto-rebuild once when job was aborted
don't do initial check twice, towards configurable interval

checkallprojects would be sent on each added config,
as well as 1 second after the backend actor was started

now we do it once all the configs have been added
contains bug
support for labels

remove "tested" label on build failure, add "needs-attention"
add "tested" label on build success (TODO: only add when all builds ok)

add "reviewed" label when comment found that starts with LGTM
(only at start to ignore conditional LGTMs)
only add/remove labels if missing/present
Merge pull request #17 from adriaanm/detailed-failure-report

Detailed failure report/labels/no double-starting/