Properly save "_resolved" and "_from" fields in npm-shrinkwrap.json.
Properly save "_resolved" and "_from" fields in npm-shrinkwrap.json.

Versions 2.x and 3.x of npm prefix internal package.json fields with
underscores, though `npm shrinkwrap` removes the underscores, so fields
like "_resolved" become just "resolved" in the shrinkwrap file.

This commit also fixes #5940.

mjmasn/meteor,chasertech/meteor,Hansoft/meteor,lorensr/meteor,jdivy/meteor,4commerce-technologies-AG/meteor,Hansoft/meteor,lorensr/meteor,jdivy/meteor,lorensr/meteor,4commerce-technologies-AG/meteor,Hansoft/meteor,DAB0mB/meteor,DAB0mB/meteor,4commerce-technologies-AG/meteor,4commerce-technologies-AG/meteor,chasertech/meteor,nuvipannu/meteor,lorensr/meteor,jdivy/meteor,nuvipannu/meteor,lorensr/meteor,Hansoft/meteor,lorensr/meteor,jdivy/meteor,Hansoft/meteor,nuvipannu/meteor,AnthonyAstige/meteor,AnthonyAstige/meteor,DAB0mB/meteor,chasertech/meteor,mjmasn/meteor,4commerce-technologies-AG/meteor,mjmasn/meteor,AnthonyAstige/meteor,DAB0mB/meteor,nuvipannu/meteor,AnthonyAstige/meteor,lorensr/meteor,AnthonyAstige/meteor,mjmasn/meteor,jdivy/meteor,Hansoft/meteor,mjmasn/meteor,AnthonyAstige/meteor,4commerce-technologies-AG/meteor,DAB0mB/meteor,jdivy/meteor,mjmasn/meteor,nuvipannu/meteor,AnthonyAstige/meteor,chasertech/meteor,Hansoft/meteor,chasertech/meteor,jdivy/meteor,nuvipannu/meteor,chasertech/meteor,mjmasn/meteor,DAB0mB/meteor,nuvipannu/meteor,AnthonyAstige/meteor,chasertech/meteor,DAB0mB/meteor,4commerce-technologies-AG/meteor