Add default value for eta_RM parameter

[jdebacker]

OG-Core version 0.13.0 added new parameters for modeling remittances. One of these, eta_RM distributes remittences by age and ability and is represented by an SxJ matrix. Since the default value of J differs in OG-USA than the default parameters for OG-Core, OG-USA needs to specific a conforming eta_RM matrix in its default calibration. This PR specifies a value of eta_RM for OG-USA.

Note that this parameter has no effect on OG-USA since the default amount of remittances in the model is 0.

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 45.22%. Comparing base (605017e) to head (d4934ed).
Report is 4 commits behind head on master.

Additional details and impacted files

@@           Coverage Diff           @@
##           master     #126   +/-   ##
=======================================
  Coverage   45.22%   45.22%           
=======================================
  Files          18       18           
  Lines        1404     1404           
=======================================
  Hits          635      635           
  Misses        769      769           

Flag	Coverage Δ
unittests	45.22% <100.00%> (ø)

Flags with carried forward coverage won't be shown. Click here to find out more.

Files with missing lines	Coverage Δ
ogusa/__init__.py	100.00% <100.00%> (ø)