Building with Dep

[Hendler]

This PR works for my system (OSX 10.13 go 1.10.1)

I'm not an expert with Dep, but it appears that running dep ensure without specifying master below failed to build [1]. Untested elsewhere, might be unique to my system.

[[override]]
  branch = "master"
  name = "github.com/couchbase/moss"

[[override]]
  branch = "master"
  name = "github.com/couchbase/ghistogram"

[[constraint]]
  branch = "master"
  name = "github.com/blevesearch/bleve"

[1] -

# github.com/blevesearch/bleve-explorer/vendor/github.com/couchbase/moss
vendor/github.com/couchbase/moss/api.go:173:15: undefined: ghistogram.Histograms
vendor/github.com/couchbase/moss/collection.go:98:13: undefined: ghistogram.Histograms
# github.com/blevesearch/bleve-explorer/vendor/github.com/blevesearch/bleve-mapping-ui
vendor/github.com/blevesearch/bleve-mapping-ui/mapping.go:105:13: undefined: bleve.IndexMapping```