Bump nodejs version to 6+ (#4272)

* let travis build against 3.x

* Cleanup dependencies and bump min version to current LTS

* Makes npm-git push all branches to -preview

* restores releases

* Bumps mime to 2.0.3 (requires node 6+)

* Bumps express to latest version

* Fixes linting issue after upgrade

* Use travis-branch for partial releases

package.json

@@ -26,11 +26,11 @@
     "body-parser": "1.18.2",
     "commander": "2.12.1",
     "deepcopy": "0.6.3",
-    "express": "4.16.0",
+    "express": "4.16.2",
     "intersect": "1.0.1",
     "lodash": "4.17.4",
     "lru-cache": "4.1.1",
-    "mime": "1.4.1",
+    "mime": "2.0.3",
     "mongodb": "2.2.33",
     "multer": "1.3.0",
     "parse": "1.10.2",
@@ -48,12 +48,9 @@
     "babel-cli": "6.26.0",
     "babel-core": "6.26.0",
     "babel-eslint": "^8.0.0",
-    "babel-plugin-syntax-flow": "6.18.0",
     "babel-plugin-transform-flow-strip-types": "6.22.0",
+    "babel-plugin-transform-object-rest-spread": "^6.26.0",
     "babel-preset-env": "1.6.1",
-    "babel-preset-es2015": "6.24.1",
-    "babel-preset-stage-3": "6.24.1",
-    "babel-register": "6.26.0",
     "bcrypt-nodejs": "0.0.3",
     "cross-env": "5.1.1",
     "deep-diff": "0.3.8",
@@ -80,7 +77,7 @@
     "prepublish": "npm run build"
   },
   "engines": {
-    "node": ">=4.6"
+    "node": ">=6.11.4"
   },
   "bin": {
     "parse-server": "./bin/parse-server"