Browser checking & builds

[SEAPUNK]

For browser builds, I think I will add another class, called BrowserClient, that will be nothing but:

class BrowserClient extends Client {
  constructor () {
    super.apply(this, arguments)
    this.isBrowser = true
  }
}

or something similar. It will let Client and ClientAbstract know when functions can utilize certain features.

For browser builds, I might have Webpack use UMD.

[SEAPUNK]

Added experimental support, will build upon it: 84ce72d45dda9bc0af0957ba036c50b9a9789d05