whitespace cleanups needed (tabs to spaces)

When I started cloud-utils long ago, I was under the misguided view that tabs could be used reliably in source code. I have now accepted that without a machine formatted (go fmt) that is not the case.

An example can be seen in cloud-utils itself that has mixed tabs and spaces for indentation. smoser fail.

So, this bug is a request to:
a.) change tabs used for indentation to 4 spaces.
b.) change the vi modeline to be correct, and make sure it is present at the end of all files.
The correct modeline for 4 spaces indentation is:
   # vi: ts=4 expandtab

Note... if someone insists that the right fix is to remove modelines entirely [1] then I would accept that, but *something* needs to insist on consistent indentation, and I used vi modelines as a mechanism for declaring the style in a file.

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[1] https://security.stackexchange.com/questions/36001/vim-modeline-vulnerabilities