update changelog.
be more specific in changelog.
change version number to 2.8.
Merge branch 'master' of github.com:akrennmair/newsbeuter
require minimum version of json-c 0.10.
Merge branch 'master' of git://github.com/akrennmair/newsbeuter

* 'master' of git://github.com/akrennmair/newsbeuter:
  require minimum version of json-c 0.10.
  change version number to 2.8.
  be more specific in changelog.
  update changelog.