install: Move more npm config into the installer object

Author: iarna

lib/install.js

@@ -191,7 +191,7 @@ function Installer (where, dryrun, args) {
   this.noPackageJsonOk = !!args.length
   this.topLevelLifecycles = !args.length
   this.npat = npm.config.get('npat')
-  this.dev = !npm.config.get('production')
+  this.dev = npm.config.get('dev') || !npm.config.get('production')
   this.rollback = npm.config.get('rollback')
   this.link = npm.config.get('link')
 }
@@ -313,8 +313,6 @@ Installer.prototype.loadAllDepsIntoIdealTree = function (cb) {
   log.silly('install', 'loadAllDepsIntoIdealTree')
   var saveDeps = getSaveType(this.args)
 
-  var dev = npm.config.get('dev') || !npm.config.get('production')
-
   var cg = this.progress.loadAllDepsIntoIdealTree
   var installNewModules = !!this.args.length
   var steps = []
@@ -327,7 +325,7 @@ Installer.prototype.loadAllDepsIntoIdealTree = function (cb) {
   } else {
     steps.push(
       [loadDeps, this.idealTree, cg.newGroup('loadDeps')])
-    if (dev) {
+    if (this.dev) {
       steps.push(
         [loadDevDeps, this.idealTree, cg.newGroup('loadDevDeps')])
     }