Added additional notice concerning compute capabilities.

* Docker build from local sources rather than Github cloned sources

* Update INSTALL instructions for docker build from Github repo

* Back to generic makefile.inc.Linux and use of env var in Dockerfile

* Back to generic makefile.inc.Linux and use of env var in Dockerfile

avoid reading beyond the end of an array in fvec_L2sqr and related functions

* Add Dockerfile

* Update documentation with Docker build/run details

- better selection of training sets for PQ and preprocessing
- GPU parameter object
- IndexIDMap fixed
- fixed redo bug in clustering

- better selection of training sets for PQ and preprocessing
- GPU parameter object
- IndexIDMap fixed
- fixed redo bug in clustering

swiggfaiss_wrap.cxx already include <numpy/arrayobject.h>, if compiled with -I/usr/lib64/python2.7/site-packages/numpy/core/include/numpy, file will be searched at /usr/lib64/python2.7/site-packages/numpy/core/include/numpy/numpy/arrayobject.h and will not be found.

* Changing a few settings for MKL on Ubuntu

This is my current configuration for MKL on Ubuntu.
I also corrected the `BLASLDFLAGS=-DFINTEGER=long` line (it should be `BLASCFLAGS`).

* Update makefile.inc.Linux

Tested and documented on MLK 2017.0.098