fix: allow rules with loader+options combination (useEntry)

[ZauberNerd]

Sometimes loaders can have only loader and options property which breaks in the current setup because the prependLoader function will only take the loader and put it as a string into the rules.use array.
This PR addresses this issue and will add an object with loader and options to the use array if options is present.

See also useEntry in webpack docs.

[stephencookdev]

Awesome! Thanks for the fix @ZauberNerd! I'll merge this into the upcoming 1.4.0 release