Fix a potential undefined variable error
Merge branch 'develop' of github.com:EllisLab/CodeIgniter into develop
Added 'application/vnd.ms-office' MIME for ppt

An export from Apple's Numbers to .ppt gives a MIME of application/vnd.ms-office
Another ppt mime type
Removed errant newline
Seriously, remove the line ending
Merge pull request #3079 from seanfahey/develop

Added MIME types for .ppt uploads
Merge remote-tracking branch 'upstream/develop' into develop