only track singular repository when comparing state of packages to upstream

Signed-off-by: Dominik Richter <dominik.richter@gmail.com>
bugfix: show outdated info only if it is defined

Signed-off-by: Dominik Richter <dominik.richter@gmail.com>
improvement: nicer styling of mirror selection dropdown dialog

Signed-off-by: Dominik Richter <dominik.richter@gmail.com>
improvement: close the mirror selection dropdown when one of its items is clicked

Signed-off-by: Dominik Richter <dominik.richter@gmail.com>
Merge pull request #20 from TelekomCloud/outdated-ui-improvements

Outdated ui improvements