Removing IMPORTEDLIBS from ${PACKAGE_NAME}_LIBRARIES

IMPORTEDLIBS should have never have been added to ${PACKAGE_NAME}_LIBRARIES.
I think I must have added this very early on in pre-TriBITS development before
anyone ever implemented the export files.
Merge remote branch 'origin/no_importedlibs_in_pkg_libs'
Updating to CMake 2.8.11 (Trilinos #6189)

With this changes, the download_cmake.py script will now download and install
CMake 2.8.11 by default.

I also updated the 'rc' and 'dev' versions from what was pulled down by
download_cmake.py.

This is needed so that all of the TriBITS Dashboard Driver run builds will
update to CMake 2.8.11 automatically.