Changes for version 0.19
- The standard is not clear on this, and some servers don't allow them, but it seems that DELETE can take a request body.
- Added serializer_options so it's possible to instantiate the serializer w/ parameters
- Fixed "Use of uninitialized value in concatenation (.) or string" warning when $self->server is not initialized
- Changes for rt #118413. Thanks to abraxxa http_headers return a combined hashref of http_headers and persistent_headers new method, clear_all_headers