Add MinusYZ model to Pyger, Add testing plot function

Add pygertest.py to repository
Add pygertest to import list in pyger.py
Add minus_yz model to constraint models file
Add minus_yz model to pyger.py
Make the minus_yz model the default predictor for tephin and tcylaft6 temperatures
Remove dependency on presence of minus_z model to generate random index list i_sims
Updated default max limits for tephin and tcylaft6
Update version number to 0.4.0

Signed-off-by: Matthew Dahmer <matthew.dahmer@gmail.com>
Add pyger test plot function.

Signed-off-by: Matthew Dahmer <matthew.dahmer@gmail.com>
Add minusyz model definition file

Signed-off-by: Matthew Dahmer <matthew.dahmer@gmail.com>
Minor tweaks and re-organization
PEP8, pychecker and whitespace cleanup
Add ConstraintMinusYZ to package __init__ and API docs
Update MinusYZ pseudo node initialization

Signed-off-by: Matthew Dahmer <matthew.dahmer@gmail.com>
Merge pull request #3 from sot/add_minusyz

Add minusyz model