ignition-math6 6.1.0 (#598)
ignition-math6 6.1.0 (#598)

* ignition-math6: update 6.1.0

* use -std=c++14 in test to fix warning

* s3 link in URL

* ignition-math6: update 6.1.0 bottle.

scpeters/homebrew-simulation,j-rivero/homebrew-simulation,osrf/homebrew-simulation