Since [Solidus 2.7 does not need ffaker gem](https://github.com/solidusio/solidus_support/pull/15#issuecomment-446900986) anymore and Solidus 2.6 will not be supported from 2019.12.16 (see [here](https://solidus.io/security/)), we should remove it.
Since Solidus 2.7 does not need ffaker gem anymore
and Solidus 2.6 will not be supported from 2019.12.16 (see here), we should remove it.