consolidate OWL

[janbiedermann]

the owl build process has several components:
opal-webpack-loader npm
opal-webpack-resolver-plugin npm
opal-webpack-compile-server gem
opal-webpack asset view helpers (currently in the owl example app)

put them all together in a opal-webpack-loader repo
which build the npms and gems
and provides the helpers
the opal-webpack-resolver-plugin should just be another export of the opal-webpack-loader npm

[janbiedermann]

owl gem/compiler server must check npm version!
(this could be part of the protocol between webpack and compile server)

[janbiedermann]

the referred commit does changes to hyper-spec, has nothing to do with this issue

[janbiedermann]

done in opal-webpack-loader 0.3.7