Interdependencies between extensions requires specific loading order.

Working on Big Bank I just noticed an issue in the loading order and interdependencies between extensions. An example of the is the Axis2 binding which requires the WSDL extension to be loaded prior to it so that autowiring can resolve WSDLDefinitionRegistry. Just loading from a directory order won't guarantee this. If we plan on supporting just dropping in of extension jars to a directory will need a means to either prescan to resolve their dependencies or load all and then begin to autowire.

This was also indirectly and briefly discussed on the mailing list http://mail-archives.apache.org/mod_mbox/ws-tuscany-dev/200609.mbox/%3c45199A79.9030009@gmail.com%3e