[FEATURE] hyperlinks for chat communication

This patch enables support for hyperlinks within
chat communication. Valid URLs inside a chat message
are colored and underlined and will be opened
with the default system browser if a user clicks
on such a hyperlink.


Change-Id: Ia6a651cad486f40a26521f11d78de0650d061b59
Reviewed-on: http://saros-build.imp.fu-berlin.de/gerrit/879
Tested-by: Jenkins CI
Reviewed-by: Richard Möhn <richard.moehn@fu-berlin.de>
Reviewed-by: Stefan Rossbach <srossbach@arcor.de>