Drop support for Google Image Search

* Remove "Photo - Search - GoogleImage" context menu

Chrome 30+ has this function.
"Easier searching by image"
http://googlechromereleases.blogspot.com/2013/10/stable-channel-update.html
"Photo - Google Image Search" Extractor doesn't need to remove

via https://github.com/syoichi/taberareloo/commit/563270dfe7f9f41f089177faa6b2bb59497c5d2d#commitcomment-4250224

Thanks, YungSang!
Merge pull request #232 from syoichi/pr37-gis

Drop support for Google Image Search