LIS — 'binary64' conformance claim

Issue: Section 13.2.2.1 mentions that implementors can use "binary64"
encoding. This should either say "base64" encoding since that is the more
accepted name for the encoding. Also, it should be explicitly noted that
doing so will reduce the interoperability of the implementation
significantly and that the resulting implementation will not be WS-I
compliant.
Suggested solution:
Either remove this claim now that the attachments WS-I profile is further
along, or at least explicitly note that the resulting implementation will
not be WS-I compliant and might not be interoperable. Also, "binary64"
should be changed to "base64".

see below