Tweak NUTS acceptance statistic, introduce number of divergent iterations for diagnosing adaptive HMC implementations
Merge branch 'develop' into feature/improve_nuts_diagnostic

Conflicts:
	src/stan/mcmc/hmc/nuts/base_nuts.hpp
Update sampler param name to be consistent with doc
Update sampler param name to be consistent with doc
Update model tests to ignore new diagnostic
Remove last reference to n_divergence
Merge pull request #352 from stan-dev/feature/improve_nuts_diagnostic

Feature/improve nuts diagnostic