Add support for UUID version 1 to UUIDFactory

Also improved documentation and minor cleanup.

The UUID1 implementation is standardized and compatible with other implementations, such as [python's uuid.uuid()](https://docs.python.org/2/library/uuid.html#uuid.uuid1). 

@adamvoncorswant @fredrikbackstrom Please have a look.
How hard is it to write this code ourselves? Wasn't there one already? I'm *really* reluctanct to adding dependencies to this application, as it's our light-weight language-only improvements utility library. Also, it's used by basically all other repos we have...