(very) basic test for authoritykeyidentifier extension class
alter cdp_location, ocsp_location, and ca_issuers_location behaviors

they now take arrays instead of strings. this allows multiple entries.
additionally the strings no longer need to be prefixed with URI: as this
is assumed. this is a slight reduction in theoretical flexibility of the
system in exchange for a significant simplification of the configuration.
update docs for R509::CaConfig to reflect new array requirements