Adding gitattributes to fix building the app on Windows

[epacke]

Git on windows checks out code using CRFL by default. While you can fix this by configuring the git client users should not have to.

This PR adds a gitattributes file to fix the problem.

To solve the problem you need to either:

Delete the repo and clone it again

...or run these commands (beware if you have made any uncommitted changes as they'll be discarded):

git checkout master
git rm --cached -r .
git reset --hard

Solves #150