Merge pull request #2263 from lambday/feature/linalg

Added vector_sum in linalg library
Added a class for GPU matrices
Merge pull request #2360 from khalednasr/feature/linalg

Added a class for GPU matrices
Implemented a class for GPU vectors
added set_const methods to GPUVector and GPUMatrix
Merge pull request #2364 from khalednasr/feature/linalg

Implemented a class for GPU vectors