Ruby bindings and sample

[ppibburr]

I made a ruby wrapper with FFI around the C portaudio example, using it as a sharedlib instead of a binary.

Also a standalone repo can be found here.
ruby-snowboy

Compiles pretty straight forward on Ubuntu Xenial 64bit

[xuchen]

Great. let me know when you finish this PR and we can review it.

[ppibburr]

Should be finished. I created a C shared lib binding, the Ruby binding that uses the C shared lib, and decoupled the portaudio stuff in to an optional tool provided by the ruby binding, allowing for other audio data sources

[xuchen]

when I followed README.md, I got error

$ ruby port-audio-sample.rb
/System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/lib/ruby/2.0.0/rubygems/core_ext/kernel_require.rb:55:in `require': cannot load such file -- ffi (LoadError)

please add sudo gem install ffi to README

[xuchen]

Great. @chenguoguo please take a look one more time before we merge.

[chenguoguo]

@ppibburr thanks for the PR. Two high level comments:

1. Could you move bindings/C to swig/Ruby/C, and then bindings/Ruby to swig/Ruby? I know you are not using the software swig, but swig also means Simplified Wrapper and Interface Generator, so we'll keep using that directory for creating wrappers.

2. Could you make files snowboy-detect-c-wrapper.{h,cc} (and other files if you copy them over) soft links instead of hard copies? This way, when we do update, we only have to update one source code.

Thanks!