Revisit dependencies and add browser ready builds

[dariocravero]

Added:

• Dist build script (borrowed from flummox) to create distribution ready builds of redux
  that can be used in a browser directly. dist/ is ignored by git.
• Configuration for cdnjs autoimport from npm.

Changed:

• Clean up package.json by removing the unused browserify section;
• Remove envify and babel-runtime as they aren't being used;
• A change log :)

Fixes #112, Fixes #115. Fixes #88.

[dariocravero]

@ooflorent could you double check that the cdnjs stuff is right? :)
@gaearon as I was saying on slack, I don't know if there's any difference with the compiled react and react-native version as both expect a global called React. Perhaps we can get rid of one of them afterwards? Maybe it's a good idea to keep them should the need to be different? Thoughts?

The uglified and gzipped version of the whole thing is at around 3kb (core (~1kb) + react (~2kb)). AMAZING :). Well done everyone for keeping redux so lean! :)

[dariocravero]

@gaearon I think you have to import it to cdnjs?

[gaearon]

Do we need to fill this from Releases page?

[gaearon]

Merged via dd83188.

[gaearon]

I slightly changed it: now react-redux exports everything there is. I don't think it makes sense to separate them. (And with the config in this PR, they exported to the same global which wouldn't work anyway.) It's like “with addons” vs “without addons” now.

[dariocravero]

Brilliant! :) Thanks!!