SCHEMA-151. Improve version number reporting

Added ProtocolVersion to describe a versioned protocol or format.
VersionInfo returns ProtocolVersions not strings, where appropriate.
KijiTableLayout tests a layout's specified protocol vs. the range
    of protocol versions supported by the client.
Update all tools / tests to use the new version API.

Signed-off-by: Milo <milo@wibidata.com>