does not work across Multiple Database : useDB

[anoopsinghbayes]

I was trying to make this work across DB ,so that every DB maintains its own collection IdentityCounter but found that its just creating it on the primary connection

I have added a test here if you want to have a look

https://github.com/anoopsinghbayes/mongoose-plugin-autoinc/blob/71780f3e5d0b65000f725e450b4e28210d2fbd74/src/__tests__/index-test.js#L436

(note could'nt install mongodb-memory-server hence my test use MongoDB instance )

[nodkz]

Please open PR with broken test. Try find time on this week to fix this problem.

Thanks.