Added periodic diagnosic collection and improved SHOW DIAGNOSTICS
show_diagnostics tests
Merge pull request #39 from mit-probabilistic-computing-project/diagnostics_engine

Diagnostics engine
Fixes examples ipython output (I pushed it live, don't fret).
Merge pull request #40 from mit-probabilistic-computing-project/ipython_docs_fix

Fixes examples ipython output (I pushed it live, don't fret).
Resolved merge conflicts with master