Add inline source maps to compiled lib

[mgcrea]

Checklist

• [X] tests and code linting passes
• [X] a test is included
• [X] documentation is changed or added
• [X] the commit message follows commit guidelines

  Affected core subsystem(s)

Babel Compilation

Description of change

Added inline sourcemaps to the lib built files to get proper stack traces:

from:

/Users/olivier/Developer/nodejs/ied/ied/lib/registry.js:97
  _assert2.default.equal(statusCode, 200, 'error status code ' + uri + ': ' + error);
                   ^
AssertionError: error status code https://registry.npmjs.org/eslint/node_modules/eslint: undefined
    at checkStatus (/Users/olivier/Developer/nodejs/ied/ied/lib/registry.js:97:20)
    at SafeSubscriber._next (/Users/olivier/Developer/nodejs/ied/ied/lib/registry.js:134:12)
    at SafeSubscriber.__tryOrSetError (/Users/olivier/Developer/nodejs/ied/ied/node_modules/rxjs/src/Subscriber.ts:247:10)
    at SafeSubscriber.next (/Users/olivier/Developer/nodejs/ied/ied/node_modules/rxjs/src/Subscriber.ts:191:23)
    at Subscriber._next (/Users/olivier/Developer/nodejs/ied/ied/node_modules/rxjs/src/Subscriber.ts:135:22)
    at Subscriber.next (/Users/olivier/Developer/nodejs/ied/ied/node_modules/rxjs/src/Subscriber.ts:95:12)
    at DoSubscriber._next (/Users/olivier/Developer/nodejs/ied/ied/node_modules/rxjs/src/operator/do.ts:93:20)

to:

../src/registry.js:48
    assert.equal(statusCode, 200, `error status code ${uri}: ${error}`)
        ^
AssertionError: error status code https://registry.npmjs.org/supertest/node_modules/supertest: undefined
    at checkStatus (../src/registry.js:48:9)
    at SafeSubscriber._next (../src/registry.js:80:19)
    at SafeSubscriber.__tryOrSetError (/Users/olivier/Developer/nodejs/ied/ied/node_modules/rxjs/src/Subscriber.ts:247:10)
    at SafeSubscriber.next (/Users/olivier/Developer/nodejs/ied/ied/node_modules/rxjs/src/Subscriber.ts:191:23)
    at Subscriber._next (/Users/olivier/Developer/nodejs/ied/ied/node_modules/rxjs/src/Subscriber.ts:135:22)
    at Subscriber.next (/Users/olivier/Developer/nodejs/ied/ied/node_modules/rxjs/src/Subscriber.ts:95:12)
    at DoSubscriber._next (/Users/olivier/Developer/nodejs/ied/ied/node_modules/rxjs/src/operator/do.ts:93:20)
    at DoSubscriber.Subscriber.next (/Users/olivier/Developer/nodejs/ied/ied/node_modules/rxjs/src/Subscriber.ts:95:12)
    at ../src/util.js

[mgcrea]

@alexanderGugel should be good now. Tell me if you see anything else.

[alexanderGugel]

Thanks.