Add HAVE_COLPACK to config_tests in class_list.cpp.py
probing sampler added (log-det)
Add BUNDLE_NLOPT option to build and link NLopt as external project
enable BUNDLE_NLOPT on travis
Merge pull request #1470 from lambday/feature/log_determinant

probing sampler added (log-det)
fix initialization bugs of factorgraph stuffs
Merge pull request #1476 from hushell/dev_bugs

fix initialization bugs of factorgraph stuffs
Random Fourier Features