Update vue-loader to v15

[deckar01]

vue-loader v15 is supposed to fix some long standing config issues. It would be nice to have this template serve as an example of its usage.

My main motivation for this issue is that I ran into some strange interaction with karma-coverage's lcov report and I'm curious if you run into any issues. Currently the detailed html coverage report does not work right for single file components. With vue-loader v15 and a few patches to istanbul I was able to get it working with perfect line coverage reporting.

[ChadTaljaardt]

dupe of #1280

Also here is a working pr : #1369

You can use it by running

vue init noamkfir/webpack#webpack-4 project