clutter-gstreamer test: add $LOAD_PATH

make to be able to run test in ruby_gnome2_base/clutter-gstreamer directory
clutter-gtk test: add $LOAD_PATH

make to be able to run test in ruby_gnome2_base/clutter-gtk directory
clutter test: add $LOAD_PATH

make to be able to run test in ruby_gnome2_base/clutter directory
gdk3-gi test: add $LOAD_PATH

make to be able to run test in ruby_gnome2_base/gdk3-gi directory
poppler test: add $LOAD_PATH

make to be able to run test in ruby_gnome2_base/poppler directory
webkit-gtk test: add $LOAD_PATH

make to be able to run test in ruby_gnome2_base/webkit-gtk directory
webkit-gtk2 test: add $LOAD_PATH

make to be able to run test in ruby_gnome2_base/webkit-gtk2 directory
clutter test: omit if Clutter::Color#hash expect arguments

Because ArgumentError occured on Travis-CI.

See commit 0c13ab000eb7e08a1e6be0d920b55659e01dc858

TODO: improve omit message.