Merged new __setitem__ logic into Develop
- This commit removes a check from the _set_data method that prevented writing scalars into vectors.  All properties are vectors now, so this check was not valid.
- Also fixed some strange retrograde code problems in hydraulic and thermal conductance where the geometry object was passed in place of geometry.pores().  This hasn't be a valid maneuver in ages, so not sure how it crept back into the code.
Merge branch 'develop' into feature/better_props

Conflicts:
	OpenPNM/Physics/hydraulic_conductance.py
	OpenPNM/Physics/thermal_conductance.py
Readded legacy add_property to Geometry, change new method to add_model
Readded legacy add_property back to Physics
Readded legacy add_property to Fluids
First attempt to enable legacy add_property and new add_model in GenericPhysics/Geometry/Fluid
- Air uses add_property, and it works like before (requiring a call to regenerate)
- Standard physics uses a mix of add_model and add_property and it also work, provided that regenerate() is called to calculate the add_property properties