Force LF

We need to choose a line-ending format. Personally, and as most people will agree, I believe LF is the best option here. This .gitattributes should convert bad line-endings to LF on push. Along with this PR, I would like to convert all CRLF files to LF, but I haven't included that, as it may break other PRs.
This comment is just to annoy @jkcclemens