MongoDB ObjectIDs can be numeric

[richardwyke]

No description provided.

[coveralls]

Coverage remained the same when pulling cb59ca0 on richardwyke:cake2.2 into f99add6 on ichikaway:cake2.2.

[moderndeveloperllc]

We don't want to remove that block entirely, just have more open conditions:

if (!ctype_xdigit($mixed)) {
return;
}

This will allow for all-digit ids AND help cut-down on the issues with the horrid strlen($mixed) !== 24 condition below it. If you don't want to make the change, I will put in a pull-request to they and clean up that logic.