HttpRequest: Store non-owning raw pointer for authConfigFactory_
HttpRequest: Use raw non-owning pointer for cookieStorage_
Rewrite AuthConfig objects using std::unique_ptr
Refactor HttpConnection and its neighbor objects
Return std::unique_ptr member as const ref

Returning raw pointer has a risk that it may be stolen by
std::shared_ptr in accident.
Fix compile error
Rewrite CookieStorage
Remove accidentally added const
HttpServer: Return bool for receiveHeader, use std::unique_ptr for headers
Use RequestSlot as pointer to avoid copying
Fix unitest compile error
Wrap BtMessage objects by std::unique_ptr instead of std::shared_ptr
Code cleanup
Use std::unique_ptr for ExtensionMessage
Use std::unique_ptr for ProgressUpdate instead of raw pointer
Use std::unique_ptr to store DHTMessages instead of std::shared_ptr
Use std::unique_ptr in DHTRegistry
Fix segmentaion fault
Use std::unique_ptr for MessageDigest
Use std::unique_ptr for AsyncResolverMan