Fix for issue 3724 (ApplicationTrustManager.java use hard coded provider and algorithm)

The new proposed fix consists on allowing the user to specify the provider and algorithm to be used by the application trust manager.  If nothing is specified, the code will try to use the SunJSEE provider and SunX509 algorithm (the behavior before the fix).  If the provider is not available, the code will try to use only the SunX509 algorithm.  If this also fails, the code will fallback and use the default algorithm of the JVM.

The previous fix generated problems for instance on Mac OS where the default algorithm is PKIX: in this case it is required to specify (using for instance java properties) the location of the trustmanager.

With the new fix, the user will be able to specify any provider or algorithm to be used, but the default behavior will be to use SunJSEE and SunX509 which works fine in most platforms.