add R509::SPKI#signature_algorithm and refactor initialize
remove pointless chomp from Cert#to_pem. Fixes #47
allow build failures on ruby-head for now since there's an issue with bundler
fix test cases broken when the fix for #47 landed.
refactor csr/spki/cert to reduce method duplication by moving a bunch of

identical methods to an included helper
some refactoring to reduce code complexity and duplication
more complexity refactoring (this time in AuthorityInfoAccess)
refactor to simplify several methods in CAConfig
refactor to reduce complexity in CSR private methods

Modify ASN1.general_name_parser to provide more readable error when not
passing a valid value
more complexity refactoring in R509::ASN1
more complexity refactoring
add CONTRIBUTING, rename README with new suffix, update gemspec [ci skip]
add actual link for issues, oops. [ci skip]
change :type param in PrivateKey and CSR

It now takes a string (RSA/DSA/EC) rather than a symbol. this was done
to try to improve consistency of keys (symbols) and values
(strings/objects) within the API. fixes #51 (and that bug also contains
much more of the rationale behind the change)

This is a breaking change so r509-ca-http will need an update.
configurable last/next_update in R509::CRL::Administrator#generate_crl
finish #48. R509::CRL::Administrator can now have pluggable backends

for storage of crl_number and crl_list data. Default is the FileReaderWriter

-Refactor R509::CRL into separate files
-Add R509::CRL::ReaderWriter
-Add R509::CRL::FileReaderWriter (default)
-Generate and save is now gone. You must call generate_crl yourself
after calling revoke_cert.
-revoke_cert now saves each revoked cert entry by entry (rather than
saving the entire list each time).
-CRL::Administrator no longer has a crl instance variable. #generate_crl
returns an R509::CRL::SignedList.