Fixed internal shared framework requires

- these requires go outside of the shared folder, and then back in to
  the index.js
- this is confusing and won't work when we pull this code out of core
- this commit cleans up the requires to make them more explicit

ghost/core/core/server/api/shared/http.js

@@ -1,6 +1,8 @@
 const url = require('url');
 const debug = require('@tryghost/debug')('api:shared:http');
-const shared = require('../shared');
+
+const Frame = require('./frame');
+const headers = require('./headers');
 
 /**
  * @description HTTP wrapper.
@@ -32,7 +34,7 @@ const http = (apiImpl) => {
             user = req.user.id;
         }
 
-        const frame = new shared.Frame({
+        const frame = new Frame({
             body: req.body,
             file: req.file,
             files: req.files,
@@ -62,7 +64,7 @@ const http = (apiImpl) => {
             const result = await apiImpl(frame);
 
             debug(`External API request to ${frame.docName}.${frame.method}`);
-            const headers = await shared.headers.get(result, apiImpl.headers, frame) || {};
+            const apiHeaders = await headers.get(result, apiImpl.headers, frame) || {};
 
             // CASE: api ctrl wants to handle the express response (e.g. streams)
             if (typeof result === 'function') {
@@ -80,7 +82,7 @@ const http = (apiImpl) => {
             res.status(statusCode);
 
             // CASE: generate headers based on the api ctrl configuration
-            res.set(headers);
+            res.set(apiHeaders);
 
             const send = (format) => {
                 if (format === 'plain') {

ghost/core/core/server/api/shared/pipeline.js

@@ -1,10 +1,13 @@
 const debug = require('@tryghost/debug')('api:shared:pipeline');
 const Promise = require('bluebird');
 const _ = require('lodash');
-const shared = require('../shared');
 const errors = require('@tryghost/errors');
 const {sequence} = require('@tryghost/promise');
 
+const Frame = require('./frame');
+const serializers = require('./serializers');
+const validators = require('./validators');
+
 const STAGES = {
     validation: {
         /**
@@ -32,7 +35,7 @@ const STAGES = {
             }
 
             tasks.push(function doValidation() {
-                return shared.validators.handle.input(
+                return validators.handle.input(
                     Object.assign({}, apiConfig, apiImpl.validation),
                     apiUtils.validators.input,
                     frame
@@ -60,7 +63,7 @@ const STAGES = {
          */
         input(apiUtils, apiConfig, apiImpl, frame) {
             debug('stages: input serialisation');
-            return shared.serializers.handle.input(
+            return serializers.handle.input(
                 Object.assign({data: apiImpl.data}, apiConfig),
                 apiUtils.serializers.input,
                 frame
@@ -83,7 +86,7 @@ const STAGES = {
          */
         output(response, apiUtils, apiConfig, apiImpl, frame) {
             debug('stages: output serialisation');
-            return shared.serializers.handle.output(response, apiConfig, apiUtils.serializers.output, frame);
+            return serializers.handle.output(response, apiConfig, apiUtils.serializers.output, frame);
         }
     },
 
@@ -203,9 +206,9 @@ const pipeline = (apiController, apiUtils, apiType) => {
             }
 
             // CASE: http helper already creates it's own frame.
-            if (!(options instanceof shared.Frame)) {
+            if (!(options instanceof Frame)) {
                 debug(`Internal API request for ${docName}.${method}`);
-                frame = new shared.Frame({
+                frame = new Frame({
                     body: data,
                     options: _.omit(options, 'context'),
                     context: options.context || {}