Fixes OATH create credential regression bug where a ':' would be adde…

…d to the account name if the optional issuer was not present.

YubiKit/YubiKit/Connections/Shared/Sessions/OATH/YKFOATHCredentialUtils.m

@@ -33,7 +33,7 @@ + (NSString *)keyFromAccountName:(NSString *)name issuer:(NSString *)issuer peri
     if (type == YKFOATHCredentialTypeTOTP && period != YKFOATHCredentialDefaultPeriod) {
         [accountId appendFormat:@"%ld/", (unsigned long)period];
     }
-    if (issuer != nil) {
+    if (issuer != nil && issuer.length > 0) {
         [accountId appendFormat:@"%@:", issuer];
     }
     [accountId appendString:name];