Update gometalinter config (#331)

* Update gometalinter config

gometalinter now uses `maligned` instead of `aligncheck`
(https://github.com/alecthomas/gometalinter/pull/367), so we need to update our
config accordingly.

* Update gometalinter

* Disable gotype linter

gotype does not seem to play nicely with the gb vendor directory. In
particular, it wants each of our dependencies to be built and installed (see
https://github.com/golang/go/issues/10969), but (empirically) it will not
accept them being installed in `pkg` but insists on them being in `vendor/pkg`.

This presents a problem because `gb build` builds the packages into `pkg`
(which doesn't seem entirely unreasonable since `.` comes before `vendor` in
`$GOPATH`). `go install github.com/x/y` does install in `vendor/pkg` but
requires us to know the name of each package.

The general conclusion of https://github.com/alecthomas/gometalinter/issues/91
seems to have been that the easiest thing to do is to disable `gotype` for now.

* Fix `unparam` lint

* Fix goshadow lint

vendor/manifest

@@ -10,7 +10,7 @@
 		{
 			"importpath": "github.com/alecthomas/gometalinter",
 			"repository": "https://github.com/alecthomas/gometalinter",
-			"revision": "5507b26af3204e949ffe50ec08ee73e5847938e1",
+			"revision": "0262fb20957a4c2d3bb7c834a6a125ae3884a2c6",
 			"branch": "master"
 		},
 		{