The path to the proxy is now only determined from the Proxy class in
the credential package.
Moved to using the GSSManager for determining the DN of the proxy for
writing out in the braindump file.
Log the what proxy will be used to determine the DN.
Removed the setting of system property X509_USER_PROXY
We already have the credential from the right proxy file at this
point.

If System property had been set, then it would create a disconnect in
the following case.
1) a user specified a proxy in the pegasus properties file or the site
catalog, that he wants to use irrespective of what is set in the
environment.
2) Pegasus would connect to RLS specifying the right path to proxy,
but the system property would have been set to the env variable value.
The properties path should have higher precedence than the environment one.