adding proxy server and server mode.
adding vcr, http request and response makers.
Adding track, recorded request and response makers.
Making recorded request serializable.
Making cassettes serializable.
Adding cassette labels.
VCR loads cassettes, records request/plays and ejects when done.
CassetteStrore  must read cassette from cassette home .
CassetteStrore  must save cassettes.
Save request body in recorded request.
Moving default charset to CassetteIO.