Cleanup CMake files.

Build the examples using unified memory only if CUDA version >= 6.0
Modify the 'reduce' and 'transform' examples.

Modified to allow testing various combinations without having to recompile.
Update several more examples.
Add the example of tabulate; change reduce and transformation
Merge branch 'radu' of https://github.com/uwsbel/Thrust-test into radu
Make changes for all example codes with managed memory.
Clean up scatter_and_gather example on device memory space.