clutter-gstreamer: remove needless note
clutter-gstreamer: show text on control

Because a segmentation fault has been fixed.
clutter-gstreamer: call Gst.init
clutter-gstreamer: remove needless note
clutter-gstreamer: remove needless note
Add Ruby 2.1 because it is already supported
gtk3: use spaces for indent

    % inplace "sed -e 's/\t/        /g'" *.rb
gtk3: remove trailing spaces

    % inplace "sed -e 's/ *$//g'" *.rb
gtk3: use " (double quote) for string literal
gtk3: use Cairo instead of Gdk::Drawable

Because it is GTK+ 3 style.
gtk3: scale drawing area to the window size
gtk3: indent
Fix broken links on GitHub
travis: temporary stop to notify