fbad_create_ad has a problem with campaign_id argument

[13bzhang]

There is a problem with campaign_id in the function fbad_create_ad. In the version available on CRAN, you had campaign_id as an argument. But in the latest GitHub version, you don't. I think it might be because it's deprecated. Anyhow, not having campaign_id as an argument is causing problems. I get an error that says:

Error in missing(campaign_id) : 'missing' can only be used for arguments

I might try to do a fix and make a pull request.

[daroczig]

Thanks for #46, I will test and merge soon

[bjeavons]

Left a comment at https://github.com/cardcorp/fbRads/pull/46/files#r114410067 but in summary, campaign ID is not a requirement for creating a ad.