report if status request returned nothing; or xml parsing will fail with irrelevant error

http://youtrack.jetbrains.com/issue/IDEA-101904#comment=27-458426
Merge remote branch 'origin/master'
test diagnostics
RUBY-12276: (refactoring) making callback API a little bit more safer
IDEA-102838 Add the link "Not YouTrack customer yet? Get YouTrack" onto the 'YouTrack server' integration
action description
NPE
reapply changes reverted by r.sh
do not check for non-represenatble characters if the file was loaded in the wrong encoding