(PP-153) Ensure SecureRandom.uuid is available

Background:
Ruby's stdlib includes SecureRandom.  In 1.9.3 SecureRandom
includes a uuid method, which is essentially a convenience
wrapper around the base random number generation.  1.8.7 did not
provide the uuid method.

Changes:
- Monkey patch 1.8 to add the uuid method (copy-paste of the code from 1.9.3)
- Add tests to verify that there is a uuid method and that it returns a
  properly formatted uuid string.
Merge branch 'issue/pp-153-add-txn-uuid-for-catalog-and-report' of github.com:kylog/puppet into issue/pp-153-add-txn-uuid-for-catalog-and-report