Remove travis badge

Author: pgleeson

README.md

@@ -144,5 +144,3 @@ Builds on [Neurotune](https://github.com/NeuralEnsemble/neurotune) and [pyelectr
 Built in viewer of cells in 3D? Mayavi?
 More closely tied to PyNN?
 
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-[![Build Status](https://travis-ci.com/NeuroML/pyNeuroML.svg?branch=master)](https://travis-ci.com/NeuroML/pyNeuroML)