C++11 standard transform

1/ set -std=c++11 flag
2/ verify in travis env
3/ transform code with clang-modernize
EDIT:
base compilers (for C++11 feature support) are gcc 4.8, clang-3.4 (used in OSX build CI)
tested to run with nupic (python)
TODO:
4/ workaround coveralls gcc 4.6 vs 4.8 issue
5/ fix c++11 problems with stdc++ on OSX

Fixes #178.