cross-validation enabled for TreeMachine, added CART notebook
data submodule updated
Added support for softmax visible units and sampling with evidence to CRBM
Merge pull request #2315 from khalednasr/rbms

Added support for softmax visible units and sampling with evidence to CRBM
Merge pull request #2310 from mazumdarparijat/documentation

cross-validation enabled for TreeMachine, added CART notebook