Bump request@2.87.0

As of 2.87.0 the hoek packages has been removed which restores
Node < 4 support

.github/PULL_REQUEST_TEMPLATE.md

-<!--
-
-**Do not bump the Request package, it breaks old Node compatiblity. It is used for downloading the binaries.**
-
-Follow https://github.com/sass/node-sass/issues/2355 for updates on when that will be resolved.
-
-Thanks for contibuting otherwise!
--->

package.json

@@ -68,13 +68,13 @@
     "nan": "^2.10.0",
     "node-gyp": "^3.3.1",
     "npmlog": "^4.0.0",
-    "request": "~2.79.0",
+    "request": "2.87.0",
     "sass-graph": "^2.2.4",
     "stdout-stream": "^1.4.0",
     "true-case-path": "^1.0.2"
   },
   "devDependencies": {
-    "coveralls": "^2.11.8",
+    "coveralls": "^3.0.2",
     "eslint": "^3.4.0",
     "fs-extra": "^0.30.0",
     "istanbul": "^0.4.2",