This changes the way the issuer CA is retrieved if no static_ca file is
used. Previously we would always download the CA using the AIA Info but
API v2 provides normally the full chain PEM upon certificate retrieval
and does not need this step. For the APIv2 case we now use the CA
provided with the certificate which required some changes to the basic
handling of CA files. APIv1 has been adapted to this new handling.
APIv2 has a fallback option to the way APIv1 handles it in case no CA
has been provided.
This adds a few basic command line parameters to allow further
customization of the configuration locations. As well as defining new
default locations for the acertmgr config files and updating the parser
with missing values, so that the config dictionary provided to the
acertmgr process after parsing is complete and no cross reference to the
configuration module is necessary. The parser error handling is also
improved.
