[FEATURE] Add ability to lazily instantiate underlying streams with 'pause' option

@jasontbradshaw

Adds the ability to supply a `pause` option to the constructor that can be used to lazily instantiate the underlying stream by preventing the `_watch` method from being executed until a `resume()` is called. This is useful in situations where one may initialize the tailing stream object before needing to use it elsewhere. 

I also fixed a bug in the way the code was merging and recognizing options by changing all instances of `Object.hasOwnProperty(someInstance, 'propertyName')` to `someInstance.hasOwnProperty('propertyName')`. 

The readme was updated to reflect the `pause` option, too.

Thanks for putting this together, BTW. It saved some time and taught me a bit about node streams. Cheers.