SERVER-1201 SERVER-3153 Showing UUID binary types better

UUIDs can already be created easily by using:
  UUID('hex-string')

However, they were still printed as BinData(3, 'base64') which
makes it difficult to debug.

This patch will print UUID objects in the same way as they
can be created, i.e. using the UUID('hex-string') format.

Fixes SERVER-1201