Better JSON validation

[stve]

Current response body validation for well-formed JSON is inherently flawed:

https://github.com/spagalloco/em-twitter/blob/master/lib/em-twitter/response.rb#L24-26

Consider parsing the response body and using successful parsing as the basis for valid responses.

[stve]

Looks like a better way to handle this is to use the delimiter argument: https://dev.twitter.com/docs/streaming-apis/processing#delimited

[akonsu]

@spagalloco I am using this to read from the firehose. For performance reasons I would prefer not to parse JSON response body, but instead redirect the body to external processes for processing. If you decide to implement JSON parsing, please consider having an option that would allow me to disable parsing.

[stve]

@akonsu thanks for the feedback. I'm going to dismiss the idea of parsing response bodies. The logic that's in place right now seems to be pretty solid and I'll handle issues with it if they come up.