Not all collection properties are stubbed with common packages

[mfen]

Our tests began failing as stubbed collections weren't being cleared on restore(). Digging, we found that at the point of parsing collection symbols to stub it was only capturing the own properties from common packages extending Mongo.Collection, e.g. matb33:meteor-collection-hooks.

This looks like #11 again, which was solved with #13 but later undone by cleanup in 376eff1

Will submit a PR to restore the fix.

[brylie]

Any status update for this issue?