added bindings for ruby

bindings/const_generator.py

bindings/ruby/Makefile

bindings/ruby/README.md

bindings/ruby/keystone_gem/Gemfile

bindings/ruby/keystone_gem/Rakefile

bindings/ruby/keystone_gem/ext/extconf.rb

bindings/ruby/keystone_gem/ext/keystone.c

bindings/ruby/keystone_gem/ext/keystone.h

bindings/ruby/keystone_gem/keystone.gemspec

bindings/ruby/keystone_gem/lib/keystone/arm64_const.rb

bindings/ruby/keystone_gem/lib/keystone/arm_const.rb

bindings/ruby/keystone_gem/lib/keystone/hexagon_const.rb

bindings/ruby/keystone_gem/lib/keystone/keystone_const.rb

bindings/ruby/keystone_gem/lib/keystone/mips_const.rb

bindings/ruby/keystone_gem/lib/keystone/ppc_const.rb

bindings/ruby/keystone_gem/lib/keystone/sparc_const.rb

bindings/ruby/keystone_gem/lib/keystone/systemz_const.rb

bindings/ruby/keystone_gem/lib/keystone/version.rb

bindings/ruby/keystone_gem/lib/keystone/x86_const.rb

bindings/ruby/keystone_gem/pkg/.gitignore