Delegate type reverse lookup for formats

[fredbi]

In type.go, function schemaInfoForType() is essentially a reverse lookup of the format registry.

Currently, there some types missing from the default registry published by go-openapi/strfmt.

PR #60 added support for "mac" (following report from go-swagger/go-swagger#1348), but some remain missing:
Formats:
[ ] TODO: missing password
[ ] TODO: missing binary

Overall, keeping this reverse lookup in sync with strfmt is a real chore. Unit testing is not very useful either.

I suggest such type reverse lookup function to be handed over to strfmt.
Custom formats could bring their own mapping too.

Any thought?