COMP: MetricImage signed/unsigned integer comparison.
COMP: Set CMP0026 for Tuner configure_file.

Comes up when using CMake master (to be 3.0).
STYLE: No extra newline in virtualenv packages CMake status.

To be consistent with the rest of the output.
BUG: Only set CMP0026 for CMake greater that 2.8.12.
Merge pull request #223 from thewtex/signed-unsigned

Signed unsigned comparison warnings and extra