Update lodash to 5.17.11 to resolve node vulnerability audit

[joeyjmorales]

[WebbizAdmin]

Why this is not merged??

[aifrim]

@WebbizAdmin tests fail

[andyedwardsibm]

https://github.com/swagger-api/swagger-node/issues/570 might be relevant. According to that, work is happening to bring the project back to life, so things like the failing Travis and these PRs might get addressed.

[DeeDeeG]

This is a very tiny PR that could help users of this package stay secure.

I use this swagger node package and would appreciate the patch to newer lodash.

Maintainers, if the various audit security errors were patched and a very small maintenance release were pushed I think existing users would greatly appreciate it. (I know I would!)

(Incidentally PR name is slightly off, the major version for lodash is 4.x, rather than 5.x)

[DeeDeeG]

Actually this PR isn't strictly necessary. On master branch, this package already depends on lodash "^4.17.2".

That means "greater than (or equal to) 4.17.2, but also less than 5.x"

If there were a new release of this package based off of the master branch, it would allow users to get up-to-date lodash, since the latest lodash (4.17.15 at the moment) is still in the 4.x series.

The fix that would be more meaningful would be for there to be a new release of this package.