Add string and stringz validator types.
Fix StringzValidator and it's spec tests.
Multiple trailing nulls are valid.
Embed message inside another and has_one relation.

Infers type by  name, or :class_name option like activerecord. Embedded
message is stored in a pascal style string that is managed automatically
Rename embedded_message to embeds_message.
Failing tests for embedding polymorphic association

Will need to implement mechanism(s) to allow binary message to specify
what message type it has encoded into it.
Merge branch 'master' of https://github.com/liaden/binary_record

Conflicts:
	binary_record.gemspec
	lib/binary_record.rb