Adding closed_at account tag to fixtures

[rafiyagi]

Description: Adding support to the closed_at tag

Testing:

• Close an account
• Reference the account and make sure you can reference the closed_at object property:

print_r( $account->closed_at );

[closed_at] => DateTime Object
(
    [date] => 2015-07-07 18:49:06
    [timezone_type] => 2
    [timezone] => Z
)

[drewish]

Can we have the testGetAccount test check that $account->closed_at is null?

[bhelx]

Any updates on this?

[drewish]

+1 Not tested but really no harm.