Auto include file name

Here's my pull request I told later.

Add %f in preferences and it will include the file name when inserting the copyright.

One project I'm working include the file name and this makes things easier to me. It won't update if the file name is changed without SublimeText. If you 'save as' with SublimeText it updates.

I haven't tested this on SublimeText 3, only with SublimeText 2, I kind of merged the changes for the master branch.