tests: cleanup integration tests

[MSalopek]

Related: #1349

Integration test wiring was changed and the test were updated where interface methods changed their signatures.

Notable changes:

• evidence handling is done through sending a message instead of calling HandleEquivocationEvidence (method was made private)
• GetTestEvidenceKeeper now returns a concrete type (evidencekeeper.Keeper)
• GetTestMintKeeper now returns a concrete type (mintkeeper.Keeper)
• GetTestGovKeeper now returns a concrete type because Params is now a collection and there is no getterfunc to include in the interface

Currently the setup is broken because there is no Begin/Endblock events.
This is the problem:

func (s *CCVTestSuite) registerPacketSniffer(chain *ibctesting.TestChain) {
	if s.packetSniffers == nil {
		s.packetSniffers = make(map[*ibctesting.TestChain]*packetSniffer)
	}
	p := newPacketSniffer()
	chain.App.GetBaseApp().SetStreamingManager(p)  // p does not implement the correct interface
	s.packetSniffers[chain] = p
}

Check this TODO to figure out where to pick this up.

// tests/integration/setup.go

// TODO: @MSalopek this was deprecated, figure out how to use it or ask @tbruyelle
// var _ baseapp.StreamingService = &packetSniffer{}