Vendor all dependencies, add docker build to makefile.

Vendor and store all dependencies. This allows us to have a makefile which
builds to a minimized docker image.

vendor/github.com/lib/pq/user_posix.go

@@ -0,0 +1,24 @@
+// Package pq is a pure Go Postgres driver for the database/sql package.
+
+// +build darwin dragonfly freebsd linux nacl netbsd openbsd solaris
+
+package pq
+
+import (
+	"os"
+	"os/user"
+)
+
+func userCurrent() (string, error) {
+	u, err := user.Current()
+	if err == nil {
+		return u.Username, nil
+	}
+
+	name := os.Getenv("USER")
+	if name != "" {
+		return name, nil
+	}
+
+	return "", ErrCouldNotDetectUsername
+}