Add SQLite support for easy setup (#336)

* Modifies schema to allow SQLite as a DB driver. SQLite is preinstalled in most OSes allowing for minimal prerequisites in the installation process.

* Removes Redis dependency and replaces "real" redis instance with ioredis-mock this is not feature complete and errors are expected.

* Updates medusa new command to only ask for Postgres credentials if the starter template has database_type === "postgres" in medusa-config.js

* Small improvements to bin resolution

* Improvements to endpoint stability

packages/medusa/src/services/__tests__/line-item.js

@@ -13,6 +13,9 @@ describe("LineItemService", () => {
     })
 
     const regionService = {
+      withTransaction: function() {
+        return this
+      },
       retrieve: () => {
         return {
           id: IdMap.getId("test-region"),
@@ -21,6 +24,9 @@ describe("LineItemService", () => {
     }
 
     const productVariantService = {
+      withTransaction: function() {
+        return this
+      },
       retrieve: query => {
         if (query === IdMap.getId("test-giftcard")) {
           return {