Document HTTP pipelining

Discuss HTTP pipelining in openConnection.

Move withConnection documentation to "Resource cleanup" section.

Clean up indenting in code examples for consistency.
More documentation cleanup
More documentation cleanup
Test case for put function
Add tests for when sending with chunked encoding
Implement chunked encoding when sending requests

Add field to Request type recording whether the entity body will be
empty, sent chunked or sent fixed length. Set appropriate defaults
depending on HTTP method including Transfer-Encoding header.

setContentLength takes care of clearing Transfer-Encoding if called.

Use Builder's chunkedTransferEncoding functions to do the actual
chunking.

Convenience functions no longer need to run the request body for size;
if the user sets a content length, fine, otherwise stream chunked.
Documentation cleanup
Merge branch 'chunked'
Ensure Empty bodies don't write content

Discard any output a body function writes if the request is a Empty
one. Might be better as something that throws an exception, but this
will do for now.
Update benchmark sample code to 0.2 API
Improve conduit benchmark by closing manager
Update performance snippet code to 0.2 API
Clean up legacy code from TestServer
Merge branch 'performance'

Update comparison benchmark and performance testing snippets to current API.
Import Builder qualified
Update README with current API
Use Builder for parameters in postForm