Add .gitignore, remove dist/ and other generated assets

[humphd]

You have a number of files and folders in git that shouldn't be there. You want to put source code in git, but leave generated/built files and folders out. Since we can use the source code to generate these, there's no need to version them. This includes things like dist/, .jar and .class files, etc.

You can add a .gitignore file to tell git what to ignore, see https://github.com/github/gitignore/blob/master/Java.gitignore for an example that works with Java projects. You can git rm -fr path to remove these.