fix: update api import paths & fix Dockerfile not copying frontend build

fixes issue #7 & #9

also remove agGrid dependency from package.json to reduce download size

cmd/citadelctl/main.go

@@ -7,8 +7,8 @@ import (
 	"github.com/BurntSushi/toml"
 	"github.com/jmoiron/sqlx"
 	"github.com/jordan-wright/email"
-	"github.com/jordanknott/project-citadel/api/pg"
-	"github.com/jordanknott/project-citadel/api/router"
+	"github.com/jordanknott/project-citadel/pg"
+	"github.com/jordanknott/project-citadel/router"
 	_ "github.com/lib/pq"
 	"golang.org/x/crypto/bcrypt"
 	"io/ioutil"