feat: Option Plugins

[wzalazar]

This PR introduces:

The ability to add more plugins for @babel/parser to istanbuljs instrumenter

related poetapp/node#230 istanbuljs/istanbuljs#205

[wzalazar]

The CI fails because I have problems with node version 6.15.1, the issue is with LAZY_LOAD_COUNT, if I change this line in local with node version 6.15.1 the command npm test is executed successfully

 // modules lazy-loaded when first file is instrumented.
-const LAZY_LOAD_COUNT = 266
+const LAZY_LOAD_COUNT = 269

I'm not sure how I can fix it, also I don't understand how my changes affect these tests

[JaKXz]

@wzalazar thank you for the contribution. Would you mind rebasing, I think we've made some changes recently that will better support this (in testing especially)

[wzalazar]

@JaKXz ok, thanks!!! I will do ;)

[coveralls]

Coverage remained the same at 96.389% when pulling e6b1b54 on wzalazar:plugins into 35cd49a on istanbuljs:master.

[coveralls]

Coverage remained the same at 96.389% when pulling e6b1b54 on wzalazar:plugins into 35cd49a on istanbuljs:master.

[wzalazar]

@JaKXz failed again, can you check out? I can't reload the task

[coreyfarrell]

Looks like a travis-ci error installing node.js on Windows. I restarted the job.

[JaKXz]

I'll leave this to @coreyfarrell or @bcoe to merge!

[coreyfarrell]

@wzalazar thank you for the contribution!