Updated .gitignore file

The cache directory is now ignored completely which breaks things if you
try to restore your sugar installation from vcs. But since a vcs is no
backup that should be okay.

Also the new upload directories were added to the gitignore file.
Merge pull request #152 from telematika/master

Updated .gitignore file.
Release 6.5.11
Release 6.5.12
Release 6.5.13
Merge remote-tracking branch 'remotes/upstream/master'
Fix for campaign mails failing after trying to send email to a unknown/unexistent email #63127