Adjust gitter link to go to new mlnet room (#42)

* Adjust gitter link

* Use badge

* Fix link

Author: danmoseley

CONTRIBUTING.md

@@ -8,7 +8,7 @@ If you are here, it means you are interested in helping us out. A hearty welcome
 
 ## Getting started:
 
-Please join the community on [gitter](https://gitter.im/dotnet). Also please make sure to take a look at the project [roadmap](ROADMAP.md).
+Please join the community on Gitter [![Join the chat at https://gitter.im/dotnet/mlnet](https://badges.gitter.im/Join%20Chat.svg)](https://gitter.im/dotnet/mlnet?utm_source=badge&utm_medium=badge&utm_campaign=pr-badge&utm_content=badge). Also please make sure to take a look at the project [roadmap](ROADMAP.md).
 
 ### Pull requests
 

README.md

@@ -44,7 +44,7 @@ We welcome contributions! Please review our [contribution guide](CONTRIBUTING.md
 
 ## Community
 
-Please join our community on Gitter [![Join the chat at https://gitter.im/dotnet/corefx](https://badges.gitter.im/Join%20Chat.svg)](https://gitter.im/dotnet/?utm_source=badge&utm_medium=badge&utm_campaign=pr-badge&utm_content=badge)
+Please join our community on Gitter [![Join the chat at https://gitter.im/dotnet/mlnet](https://badges.gitter.im/Join%20Chat.svg)](https://gitter.im/dotnet/mlnet?utm_source=badge&utm_medium=badge&utm_campaign=pr-badge&utm_content=badge)
 
 This project has adopted the code of conduct defined by the [Contributor Covenant](http://contributor-covenant.org/) to clarify expected behavior in our community.
 For more information, see the [.NET Foundation Code of Conduct](https://dotnetfoundation.org/code-of-conduct).