Add seeding of the system user's community users

[Oaphi]

closes #1489

blocks #1487

[Oaphi]

Note: I opted for trust level equal to 4, but not sure what's the trust level for the user's community users on production communities - happy to adjust if the assumption is incorrect.

[cellio]

Note: I opted for trust level equal to 4, but not sure what's the trust level for the user's community users on production communities - happy to adjust if the assumption is incorrect.

In production "trust level" is NULL, but mine and Art's are both 5. I'm not sure what we use this for today other than category read access (which System wouldn't care about). I'd guess we should go with NULL, and I'll defer if another reviewer says something different.

[Oaphi]

Note: I opted for trust level equal to 4, but not sure what's the trust level for the user's community users on production communities - happy to adjust if the assumption is incorrect.

In production "trust level" is NULL, but mine and Art's are both 5. I'm not sure what we use this for today other than category read access (which System wouldn't care about). I'd guess we should go with NULL, and I'll defer if another reviewer says something different.

Perfect, thanks! I'll change it to nil then - level 4 was just a placeholder value until someone with production access could verify.

[cellio]

LGTM. Needs review by a better Rubyist.