HttpTransport implementation (#6)

i took a first stab at #6, doc-blocks and especially tests are yet missing but will be completed - i'd be first interested in some feedback from @bzikarsky? :) 

Is that - at least a bit - like you'd thought it should? `HttpTransport` is mainly based on `UdpTransport`.. i'm open to suggestions, if we should make it more flexible at certain points?
Magic number? I'd prefer reading until `\r\n\r\n` is found. Then we can add a simple comment that we read the headers in 1024B chunks