Be more forgiving in parsing verifier IDs

RFC 4648's Base32 is made to be forgiving for users doing manual entry
of the digits. For this reason we want to be able to parse lowercase
letters as uppercase and number 0 (zero) as letter O along with number
1 (one) as letter I.

Change-Id: Ide760aff84f97c3e06af8bf8d006f36c74033a41