As suggested by Joshua, this commit adds the 2-clause BSD license as a
comment block to the top of every source file.
For the first pass, I've just added myself for simplicity. I encourage
everyone to add themselves as copyright holders of any file they've
added or modified in some significant way. If I've added myself in
error somewhere, feel free to replace it with the appropriate copyright
holder instead.
Going forward, all new source files should include a license header.
This API was returning a "const char*" and it was unclear who took care
of the underlying memory. Returning a String makes that obvious.
Also make sure we close the /etc/passwd file when we're done with it.