ssl-proxy: do not check for file modification time on each request

do not stress file system, if possible

merge configs for CRL and cert cache into a single one.
Introduced new property 'org.globus.jglobus.cert.cache.lifetime'
which controls CRL cache and cert cache.

For backward compatibility, the value of org.globus.jglobus.crl.cache.lifetime
will be taken for CRL if defined.