Bump bluebird from 2.9.25 to 3.7.1

Bumps [bluebird](https://github.com/petkaantonov/bluebird) from 2.9.25 to 3.7.1.
- [Release notes](https://github.com/petkaantonov/bluebird/releases)
- [Commits](petkaantonov/bluebird@v2.9.25...v3.7.1)

Signed-off-by: dependabot-preview[bot] <support@dependabot.com>

package.json

@@ -25,7 +25,7 @@
   "main": "dist/index.js",
   "dependencies": {
     "babel-runtime": "7.0.0-beta.3",
-    "bluebird": "2.9.25",
+    "bluebird": "3.7.1",
     "forest-express": "5.3.0",
     "http-errors": "1.7.2",
     "lodash": "4.17.13",

yarn.lock

@@ -1388,10 +1388,6 @@ bitwise-xor@0.0.0:
   version "0.0.0"
   resolved "https://registry.yarnpkg.com/bitwise-xor/-/bitwise-xor-0.0.0.tgz#040a8172b5bb8cc562b0b7119f230b2a1a780e3d"
 
-bluebird@2.9.25:
-  version "2.9.25"
-  resolved "https://registry.yarnpkg.com/bluebird/-/bluebird-2.9.25.tgz#6e36bd04064d9534c07160b9f7f26c5a738fe16a"
-
 bluebird@3.5.1:
   version "3.5.1"
   resolved "https://registry.yarnpkg.com/bluebird/-/bluebird-3.5.1.tgz#d9551f9de98f1fcda1e683d17ee91a0602ee2eb9"