Set partition labels

[djmaze]

We should set a label for each partition. This makes it easy to e.g. find the "root" partition regardless of the partition layout (which might differ between devices or setups).

[umiddelb]

Partition labels are a good idea in general, but you should prevent duplicates. Otherwise tools like df will get confused.

The ODROID boot.ini uses UUIDs to identify the root filesystem. Either you change the UUID in boot.ini or you pass the UUID to the mkfs command. Using UUIDs instead of device nodes is really helpful since the device numbering may vary between different kernels (3.10 vs. mainline).