Unetpy support for connecting to older versions of UnetStack.

[notthetup]

Currently when unet.py (> v3.1.0) tries to connect to a version of UnetStack running an older fjage (< v3.1.0), getting parameters is causes KeyError. org-arl/fjage#180 should fix the KeyError but the functionality is still missing.

This is caused by the movement of the ParameterAPI from UnetStack into fjage. The issue comes because the full names of the ParameterReq and ParameterRep messages changed in this movement. So the newer unet.py library sends a org.arl.fjage.param.ParameterReq but the older version of UnetStack expects a org.arl.unet.ParameterReq.

Previously, unet.py injected the setter and getter methods onto the AgentID class to generate those messages. Now (> fjage 1.7.0) AgentID class already has those methods but use the new org.arl.fjage.param.ParameterReq.

[notthetup]

This outlines a potential solution : #43 (comment)