clutter test: omit if Clutter::Color.hash expect arguments

Because ArgumentError occured on Travis-CI.

See commit 0c13ab000eb7e08a1e6be0d920b55659e01dc858

TODO: improve omit message.
travis: add "ruby-head"

Because "ruby-head" version on Travis-CI came to be
automatically updated.
popple: remove duplicated code
poppler: use the same naming rule in the same file
poppler: run make automatically
clutter-gstreamer test: move clutter-gstreamer after gstreamer

Because clutter-gstreamer depends on gstreamer.
clutter-gstreamer test: add a check whether Makefile exists
poppler test: use false to represent failure exit
clutter-gtk test: move clutter-gtk after gdk3 and gtk3

Because clutter-gtk depends on them.
clutter-gtk test: add a check whether Makefile exists
gdk3-gi test: we don't run the test at this time

Travis workaround #200:

> It is reasonable that we don't run the test for gdk3-gi on Travis CI for now.