Improve shown error when Stampede is trying to replicate from a MongoDB whose version is not 3.2

[gortiz]

The issue #130 reported by @p1nox indicates that when Stampede is trying to replicate from a MongoDB 3.4, the error shown is (syntethized) the following:

2016-12-22T04:01:30.851 ERROR 'RecoveryService' c.t.m.r.ReplCoordinator Fatal error while starting recovery mode: Not supported yet
2016-12-22T04:01:30.854 ERROR 'RecoveryService' c.t.m.r.MongodbReplBundle Catched an error on the replication layer. Escalating it
2016-12-22T04:01:30.855 ERROR 'RecoveryService' c.t.s.StampedeService Error reported by replication supervisor. Stopping ToroDB Stampede

It should say something like "It is not supported to replicate from MongoDB version whatever"