switch the ci build to azure devops. (#209)

Author: Wenbing Li

README.md

@@ -3,7 +3,7 @@
 
 | Linux | Windows |
 |-------|---------|
-| [![Build Status](https://travis-ci.org/onnx/onnxmltools.svg?branch=master)](https://travis-ci.org/onnx/onnxmltools) | [![Build status](https://ci.appveyor.com/api/projects/status/d1xav3amubypje4n?svg=true)](https://ci.appveyor.com/project/xadupre/onnxmltools) |
+| [![Build Status](https://dev.azure.com/onnxmltools/onnxmltools/_apis/build/status/onnxmltools-linux-conda-ci?branchName=master)](https://dev.azure.com/onnxmltools/onnxmltools/_build/latest?definitionId=3?branchName=master)| [![Build Status](https://dev.azure.com/onnxmltools/onnxmltools/_apis/build/status/onnxmltools-linux-conda-ci?branchName=master)](https://dev.azure.com/onnxmltools/onnxmltools/_build/latest?definitionId=3?branchName=master)|
 
 # Introduction 
 ONNXMLTools enables you to convert models from different machine learning toolkits into [ONNX](https://onnx.ai). Currently the following toolkits are supported:
@@ -140,4 +140,4 @@ be added in *tests_backend* to compute the prediction
 with the runtime.
 
 # License
-[MIT License](LICENSE)
+[MIT License](LICENSE)