Issue 1386 iframed oauth flow

Here is iframing! based on `add-a-broker` and should be reviewed afterwards.
On 04/12/2014 14:12, Vlad Filippov wrote:
> In app/scripts/lib/auth-errors.js:
>
>> @@ -101,7 +103,9 @@ function () {
>>      1017: t('Unexpected error'),
>>      1018: t('Your verification email was just returned. Mistyped email?'),
>>      1019: t('Valid email required'),
>> -    1020: t('Enter a valid email address. firefox.com does not offer email.')
>> +    1020: t('Enter a valid email address. firefox.com does not offer email.'),
>> +    1021: t('Channel timeout'),
>> +    1022: t('Firefox Accounts can only be placed into an IFRAME on approved sites')
>
>     We are trying to convey
>
> Most users should never see this error though? So this can be pretty generic
>
> —
> Reply to this email directly or view it on GitHub
> <https://github.com/mozilla/fxa-content-server/pull/1796/files#r21340778>.
>


Right! This should be an RP developer facing string. Their user's should 
not see this unless the RP dev really messes up.

Shane