do not build main binary for tests
Merge pull request #67 from tschottdorf/mktest

do not build main binary for tests
Adding unit tests to kv/local_kv_test.go

Generalizing gossip network simulation so that it can be used to test gossip networks more broadly

Adding unit tests for kv/dist_kv.go and fix user permission bug in
storage/prefix.go caught by the tests