gtksourceview3: break a long array literal
gtksourceview3: check Makefile existence
gtksourceview3: use false for unexpected exit
gtksourceview3: remove needless load paths
gtksourceview3: remove an unused variable
vte3-gi: don't use "_full" in method name

Because it isn't Rubyish method. If we want to provide both simple and
complex APIs, we can provide pseudo overload method with variable
length arguments, options Hash and so on in Ruby. We don't need to add
"_full" suffix in method name.

TODO: Run any command in the test.
gstreamer: add a test
gstreamer: fix a bug that Gst.init is failed

Output array handling in Ruby/GObjectIntrospection was changed.

GitHub: #232

Reported by saepia. Thanks!!!
gstreamer: add gstreamer.rb for Bundler's autoload

GitHub: fix #232

Reported by saepia. Thanks!!!
clutter: fix a bug that needless $0 is added to init arguments
clutter-gst: fix a bug that needless $0 is added to init arguments
clutter-gstreamer: add clutter-gstreamer.rb to support Bundler's autoload
clutter-gtk: fix a bug that needless $0 is added to init arguments
Don't run gdk3-no-gi test
Enable gstreamer test
gdk3: backport Gdk::Event::PROPAGATE and STOP
travis-before-script.sh: add ppa repository

Ubuntu 12.04 has not libgstreamer1.0-dev package in official repository.

```
$ cat /etc/lsb-release
DISTRIB_ID=Ubuntu
DISTRIB_RELEASE=12.04
DISTRIB_CODENAME=precise
DISTRIB_DESCRIPTION="Ubuntu 12.04.4 LTS"

$ LANG=C apt-cache show -n libgstreamer1.0-dev
N: Unable to locate package libgstreamer1.0-dev
N: Couldn't find any package by regex 'libgstreamer1.0-dev'
E: No packages found
```

It needs add ppa repository which is ppa:gstreamer-developers/ppa.
travis-before-script.sh: add `echo "yes"` to select yes
travis: don't require input
travis: use PPA only if it is needed