Fortunately GIT has a very easy solution for this, just run the following command on the file or path you want to ignore the changes of:
git update-index --assume-unchanged <file>
If you wanna start tracking changes again run the following command:
git update-index --no-assume-unchanged <file>
source: http://blog.pagebakers.nl/2009/01/29/git-ignoring-changes-in-tracked-files/