remove unused instance variable
Merge pull request #76 from databus23/patch-2

remove unused instance variable from CRL::Administrator
Updated r509::CRL::FileReaderWriter.read_list to iterate and yield which removes the
need for a reference to a r509::CRL:Admistrator object.
Update docs to reflect new behavior
Merge pull request #80 from jsuhre/decouple_crl_readerwriter_administrator

Decouple CRL::FileReaderWriter from CRL::Administrator
copy to clipboard is optional
Both interactive and non-interactive parse opts into opts

- copy csr/cer to clipboard on the mac is optional
- both parse subjects into an array
- option for self signed from cli
- put interactive prompt values into opts
DRY generation and output of csr/cert