Updated link in CONTRIBUTING.md
Merge pull request #750 from rhyolight/update-readme

Updated link in CONTRIBUTING.md
Adding readme file
Adding content to spatial pooler example readme
Merge pull request #754 from zacg/master

Readme for Spatial Pooler Example
"ie" replaced by "i.e."
"htmtest" only with PyNode tests moved to "/tests"

"htmtest" was splitted in two versions: one only with C++ tests which
was moved to "nupic.core" and another only with PyNode (c++ region
implementation for Python projects).
.gitignored updated to ignore "/nta" folder
CMake file is able to build submodules
A improved version of CMake file

-Removed standard libraries (libapr, libs,etc) stuff;
Fixed -lc++abi issue
Fixed -gfull issue
Update .gitmodules
Update .gitmodules
Updated SHA
Update SHA
Replaced "nupic.core" to "nupic_core" (compliance with file name convention)
Update SHA
Force Travis to compile
Merge branch 'master' of https://github.com/DavidRagazzi/nupic