Daniele E. Domenichelli authored Apr 02, 2014 and Brad King committed May 12, 2014

When a project is packaged for redistribution the local package
registries should not be updated or consulted.  They are for developers.

Add variables to disable use of package registries globally:

* CMAKE_EXPORT_NO_PACKAGE_REGISTRY that disables the export(PACKAGE)
  command
* CMAKE_FIND_PACKAGE_NO_PACKAGE_REGISTRY that disables the User Package
  Registry in all the find_package calls.
* CMAKE_FIND_PACKAGE_NO_SYSTEM_PACKAGE_REGISTRY that disables the
  System Package Registry in all the find_package calls.

Update documentation and unit tests.