diagnostics.py - change to using fig.tight_layout
diagnostics.py - change to using fig.tight_layout

trying to fix some error about backends on OSX:

/Users/tobeycarman/.pyenv/versions/kitchen-sink/lib/python2.7/site-packages/matplotlib/tight_layout.py:225: UserWarning: tight_layout : falling back to Agg renderer
  warnings.warn("tight_layout : falling back to Agg renderer")

tobeycarman/dvm-dos-tem,tobeycarman/dvm-dos-tem,tobeycarman/dvm-dos-tem,tobeycarman/dvm-dos-tem,tobeycarman/dvm-dos-tem,tobeycarman/dvm-dos-tem