cleanup Rakefile and recreate gemspec
update Gemfile
update link to Visual C++ Express
Merge branch 'master' of github.com:ruby-opencv/ruby-opencv
bump up version
fix Manifest.txt and recreate gemspec
update documents
add gem-compile to Gemfile
fix DEVELOPERS_NOTE.md
update Rakefile and Manifest.txt
update description of the way to create gem
bump up version
Merge branch 'master' into documentation

Conflicts:
	Gemfile
	Rakefile