Remove lodash dependency to decrease global package size

[kraynel]

Hi!

I am not sure if this repo is still active, but here is my contribution anyway.
I noticed that installing request + request-promise-native adds a whole 10Mb to my project.

The full Lodash is bundled and needed for only 4 basic functions (+1 for build).
I switch from lodash.isArray to Array.isArray, please tell me if this is a problem.

[coveralls]

Coverage decreased (-0.003%) to 98.87% when pulling 38d3507 on kraynel:remove-full-lodash-dependency into 45c01b7 on request:master.

[coveralls]

Coverage increased (+1.1%) to 100.0% when pulling 6c854e6 on kraynel:remove-full-lodash-dependency into 45c01b7 on request:master.

[kraynel]

I've just seen #7, so I guess you can close that one if you did not change your opinion on the subject.

[2PacIsAlive]

+1, already discussed in #7 but this size reduction would still be beneficial for us :)

[kraynel]

Ok I tried something new and extracted the lodash function into the lib. It has the advantage of adding no overhead and being self-contained, with the drawback of not profitting from any of the future lodash fixes.

As the copied code is quite short, I guess this could be acceptable.

[odinho]

Yes please!

This is the only thing dragging in the full lodash anymore, and we could save space in our build artifacts.

Was going to write a similar PR, but this is already better.

[sseide]

I created a patch too before seeing this and have thrown out all of the lodash functions used in production dependencies except isObjectLike() with one more generic typeOf() function. But is easily possible to inline this single function too.

Afterwards lodash.flatten is only used as devDependency...

Any thoughts as this patch here has not been merged by now?
https://github.com/sseide/promise-core/tree/reduce_lodash_dep

And hoping for lodash v5 is probably like waiting for Godot...