Request::with_stream to use a different NetWorkStream in Client

added benches for mocking out the tcp process
adjust representation of internal Items
Merge pull request #36 from seanmonstar/issue-35

adjust representation of internal Items
Added Typeable dependency.
Refactor Header representation to not store the raw representation

This disallows reparsing, but since that can be a significant source
of errors I think this is actually beneficial.

This also refactors to avoid storing the TypeId, though that is less
of a gain.
ssl for the client
Disallow parsing as multiple types to prevent transient errors.
Merge pull request #37 from seanmonstar/ssl

ssl for the client
Merge pull request #38 from reem/persistent-headers

Refactor Header representation to not store the raw representation