Updating build instructions to include BLAS support (#1183)
* Updated build information
First update to the build instructions to include BLAS.
* Update README.md
* Update information about BLAS
* Better BLAS explanation
Adding a clearer BLAS explanation and adding a link to download the CUDA toolkit.
* Better BLAS explanation
* BLAS for Mac
Specifying that BLAS is already supported on Macs using the Accelerate Framework.
* Clarify the effect of BLAS
* Windows Make instructions
Added the instructions to build with Make on Windows
* Fixing typo
* Fix trailing whitespace
