Bundler fails unless sinatra is already installed.

[jwoffindin]

The dubai.gemspec file requires dubai.rb, and this breaks unless all dependencies are
already installed. E.g. a bundle install in a vanilla install breaks with

There was a LoadError while evaluating dubai.gemspec:
cannot load such file -- sinatra/base from
blah blah ..../bundler/gems/dubai-918236eaa64b/dubai.gemspec:3:in `<main>'

Gemspec only needs version, so split it into a separate file and include that only.

Also bumped the version, 0.0.1 -> 0.0.2; not sure if that's okay.

[mattt]

Thanks for the patch, @jwoffindin. It's only recently that I realized what exactly was going on with the version convention in Ruby gems. Unfortunately misleading that gem installation works locally, you know?

[jwoffindin]

No problem & thanks for the great gem !