Update pbi-manager, libsh and warden to use PC-BSD CDN for packages

- Updated pbi-manager and libsh to current versions used by PC-BSD

- Brought in PC-BSD xtrafiles for various CDN mirrors to be used

- Updates pbi-wrapper Makefile to use new naming convention used by
  pbiwrapper. Also updated to compile for i386 and amd64 architectures.

- Updated the warden to understand new syntax of mirror functions

- Modified build system to work with the new changes