Apache Pinot

When running `mvn clean install -DskipTests -Pbin-dist` on master, I got a failure: `on project pinot-jdbc-client: *Some files do not have the expected license header`.* 

The specific files were:
```[INFO] Checking licenses...
[WARNING] Unknown file extension: /Users/kenkrugler/git/pinot-ken/pinot-clients/pinot-jdbc-client/.externalToolBuilders/Maven_Ant_Builder.launch
[WARNING] Missing header in: /Users/kenkrugler/git/pinot-ken/pinot-clients/pinot-jdbc-client/maven-eclipse.xml```
Is this due to cruft in my filesystem, or some missing exclusions that ought to be there, or something else?

I think there are some ignored files without header?

Yes - e.g. the `maven-eclipse.xml` looks like a generated file (not under source control). Same for  the `.externalToolBuilders` directory

-Dlicense.skip=true can be a temporary solution. (I experienced this issue yesterday also)
Seems this is a common issue facing users; the tutorial wiki needs to be updated to clarify (e.g., what it means, identify the files missing headers, temp or full solution).