Add support for updateByEmail to the Contact resource

[dominics]

Fixes #84

[flexgrip]

Is this on packagist yet? And also is this the reason why I haven't been able to update a contact by email? I can't figure it out. I've been getting a 204 response. But the contact in hubspot is not updating. Example:

            # Instantiate new hubspot factory using the FD api key
            $hubspot = \SevenShores\Hubspot\Factory::create('123');

            # URL decode the orignal email
            $update_email = $orig_email;

            # Get the contact from the original form submit
            $contact = $hubspot->contacts()->getByEmail($update_email);

            # Instantiate the current time
            $now = Carbon::now();

            # Now use their vid to update the contact with the proper name, phone and email
            $props["properties"] = [
                array("property" => "email", "value" => $email),
                array("property" => "firstname", "value" => $name),
                array("property" => "phone", "value" => $phone),
                array("property" => "fd_account_create_date", "value" => $now->timestamp * 1000),
            ];

            # Last, update the contact.
            $update_contact = $hubspot->contacts()->update($contact->vid, json_encode($props));