deps: upgrade to npm 2.14.16

Another day, another LTS!

The changelog for this version can be found here: https://github.com/npm/npm/releases/tag/v2.14.16

Interesting changes:

• 24b13fb #11158 and 5c0e4c4 #10940 which include patches by @orangemocha that they had asked about in #4872
• 64995be 75ab216 a9f6fe9 649c193 94cb05e 6541690 255be6f 9e84fa4 8a587b0 bf812a5 #10903 Get rid of nock from tests, and get Travis green, which might hopefully also make CI in general more reliable. (@zkat and @iarna)
• A few other general bugfixes.
• Lots of doc updates/fixes.

r: @Fishrock123 r: @iarna