email intercom data is managed by BWP requirements class already
add the ATTACHMENT_MAX_FILESIZE email requirement constant
intercom_data should be static so we can call it with call_user_func
alternate function for display
just return an empty array for now
display any service constant
add the service constants to the intercom data
Merge pull request #391 from humanmade/feature/service-intercom-data-function-390

Feature/service intercom data function