Add Coverity badge

Author: vmuriart

.gitignore

@@ -54,3 +54,6 @@ _UpgradeReport_Files/
 Backup*/
 UpgradeLog*.XML
 UpgradeLog*.htm
+
+# Coverity
+cov-int/

CHANGELOG.md

@@ -17,6 +17,7 @@ This document follows the conventions laid out in [Keep a CHANGELOG][].
 -   Added `Slack` chat (#384)(#383)(#386)
 -   Added function of passing an arbitrary .NET object as the value
     of an attribute of PyObject (#370)(#373)
+-   Added Coverity (#390)
 
 ### Changed
 

README.md

@@ -3,6 +3,7 @@
 [![appveyor shield][]](https://ci.appveyor.com/project/pythonnet/pythonnet/branch/master)
 [![travis shield][]](https://travis-ci.org/pythonnet/pythonnet)
 [![codecov shield][]](https://codecov.io/github/pythonnet/pythonnet)
+[![coverity shield][]](https://scan.coverity.com/projects/pythonnet)
 
 [![license shield][]](./LICENSE)
 [![pypi package version][]](https://pypi.python.org/pypi/pythonnet)
@@ -86,6 +87,8 @@ int32
 
 [codecov shield]: https://img.shields.io/codecov/c/github/pythonnet/pythonnet/master.svg?label=Codecov
 
+[coverity shield]: https://img.shields.io/coverity/scan/7830.svg
+
 [license shield]: https://img.shields.io/badge/license-MIT-blue.svg?maxAge=3600
 
 [pypi package version]: https://img.shields.io/pypi/v/pythonnet.svg