Add support for GPT partition names (#741424)

Embedded devices (Android) use GPT partition names to identify
partitions, instead of file system labels.  Add support for viewing and
changing them.

As partition names are used to provide unique identification they are
never copied when copying the contents of one partition to another.

Note that GNU/Linux uses file system labels, UUIDs or device names for
identification during the boot process and afterwards so while partition
names can be used, they are optional and purely for user information.

Bug 741424 - Add support for GPT partition names