closes #28 on voloko/twitter-stream by re-raising exceptions once handled

[jacegu]

We have been bitten by this exception swallowing pretty badly last week. We lost a huge amount of time due our inability to track errors (we weren't even using this gem but other gem that actually does).

Added a spec to verify that if anything goes wrong while delivering items, the actual exception is popped after handling the connection instead of just returning.

[auxbuss]

+1 to this.

[rud]

I've added to the discussion over at issue #28, please have a look there

[rud]

Similar fix included in pull-request #30, closing this.