Change CMAKE version requirement to 2.8

ExternalProject is a feature added in version 2.8
Adding basic support for pkg-config based configuration management, for gcc based distributions.
Bumped the SOVERSION to 2 to account for ABI changes
Fixed several typos in .pc file
Cleanup of txt not in the spirit of the clMath Apache license
Adding CUDA_PATH as an option for OPENCL_ROOT
CUDA uses Win32 to store 32 bit libraries

travis build;change the client default device to cpu in order to run test on the remote server (does not have gpu);need to link to acml in order to build test-correctness
Merge branch 'develop' of https://github.com/TimmyLiu/clBLAS into develop