Target information retrievers for WS services default URL '/arex' path

ARC client plugins implements the 'default URL guessing' approach in case the only hostname are passed to the '-c' or similar options.

However the current code provides 'https://hostname' URL that is ambiguous and cannot be used without '/arex' in the URL path. This results in MCC Plexer: UNKNOWN_SERVICE_ERROR in the A-REX log and anyway don't allow infoquery with this plugin.

This MR modifies the 'guessing' functions to produce 'https://hostname/arex' URL that will work in case of default 443 port setup.

This allows for example to use: arcinfo -I org.ogf.glue.emies.resourceinfo arc.hostname and even without -I will be used as successful LDAP GLUE2 fallback in case LDAP is unavailable.