Meteor 3.0 compatibility

[dengribar]

The current version of the package is not compatible with Meteor 3.0:

error: Conflict: Constraint minimongo@1.0.9 is not satisfied by minimongo 2.0.1.
Constraints on package "minimongo":
* minimongo@~2.0.1 <- top level
* minimongo@1.0.9 <- dburles:factory 1.5.0

To make it compatible, we simple need to add 3.0 to api.versionsFrom

Since "sync" API doesn't work in Meteor 3.0+, I put all "sync" API tests under isPreMeteor3 condition.
And in "async" tests I fixed issues with using synchronous MongoDB API: findOne, update, remove, count