Implement HTTP response parser
Implement HTTP stream

While there, define and use Headers as std::map from std::string
to std::string.
Implement HTTP request serializer
Implement HTTP response class
Implement HTTP request (= the verb, not the noun)
Implement basic HTTP client
Fix unit test and reduce verbosity
Implement body-terminated-by-EOF semantic
.gitignore test/protocols/http
Merge pull request #57 from TheTorProject/feature/http_client-v2

Add basic HTTP client functionality