Change default file system to ext4 (#711114)

In the Create New Partition dialog use ext4 as the default choice for
new file systems.  It has been the preferred file system of
distributions for many years.  Use ext3 and ext2 as second and third
choice defaults.  This handles RHEL/CentOS 5.x which doesn't support
ext4.

Bug #711114 - Change default fs to ext4
List ext4 in the GParted Manual (#711114)

Bug #711114 - Change default fs to ext4