Finding areas that are untested and need love (#4131)

* Makes InstallationRouter like others

* Adds testing for Range file requests

- Fixes issue with small requests (0-2)

* Revert "Makes InstallationRouter like others"

This reverts commit e2d2a16ebf2757db6138c7b5b33c97c56c69ead6.

* Better handling of errors in FilesRouter

* Fix incorrectness in range requests

* Better/simpler logic

* Only on mongo at it requires Gridstore

* Open file streaming to all adapters supporting it

* Improves coverage of parsers

* Ensures depreciation warning is effective

* Removes unused function

* de-duplicate logic

* Removes necessity of overriding req.params.className on subclasses routers

* Use babel-preset-env to ensure min-version compatible code

* removes dead code

* Leverage indexes in order to infer which field is duplicated upon signup

- A note mentioned that it would be possible to leverage using the indexes on username/email to infer which is duplicated

* Small nit

* Better template to match column name

* Restores original implementation for safety

* nits

src/Routers/InstallationsRouter.js

@@ -4,26 +4,13 @@ import ClassesRouter from './ClassesRouter';
 import rest from '../rest';
 
 export class InstallationsRouter extends ClassesRouter {
+  className() {
+    return '_Installation';
+  }
+
   handleFind(req) {
     const body = Object.assign(req.body, ClassesRouter.JSONFromQuery(req.query));
-    var options = {};
-
-    if (body.skip) {
-      options.skip = Number(body.skip);
-    }
-    if (body.limit || body.limit === 0) {
-      options.limit = Number(body.limit);
-    }
-    if (body.order) {
-      options.order = String(body.order);
-    }
-    if (body.count) {
-      options.count = true;
-    }
-    if (body.include) {
-      options.include = String(body.include);
-    }
-
+    const options = ClassesRouter.optionsFromBody(body);
     return rest.find(req.config, req.auth,
       '_Installation', body.where, options, req.info.clientSDK)
       .then((response) => {
@@ -31,26 +18,6 @@ export class InstallationsRouter extends ClassesRouter {
       });
   }
 
-  handleGet(req) {
-    req.params.className = '_Installation';
-    return super.handleGet(req);
-  }
-
-  handleCreate(req) {
-    req.params.className = '_Installation';
-    return super.handleCreate(req);
-  }
-
-  handleUpdate(req) {
-    req.params.className = '_Installation';
-    return super.handleUpdate(req);
-  }
-
-  handleDelete(req) {
-    req.params.className = '_Installation';
-    return super.handleDelete(req);
-  }
-
   mountRoutes() {
     this.route('GET','/installations', req => { return this.handleFind(req); });
     this.route('GET','/installations/:objectId', req => { return this.handleGet(req); });