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

do not stress file system, if possible.
ssl-proxy:  DRY cleanup
ssl-proxy:  make cert cache life time configurable

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.