Remove company_identification_code_designator in favor of 10 digit company_identification

To support backwards-compatibility, if a 9-character string is given,
prepend with 1 indicating the identifier is an EIN. It's not perfect
backwards compatibility, but I think is a reasonable compromise. I don't
necessarily expect to give this compatibility "feature". Fixes #21
Bump to 0.4.7
Merge branch 'master' of github.com:jm81/ach