Upgrade Node to >= 6 and asar to ^1.0.0

[malept]

This is in response to the changes in electron/asar#165. This module only uses extractFile, so it should be fine with zero changes other than to package.json.

[carterbs]

@MarshallOfSound wondering if this will be merged in the coming weeks. Would be great to have our audit return 0 vulnerabilities.

[malept]

This is technically a vulnerability that can be ignored for this module, as electron-winstaller doesn't use any of the functionality provided by the transitive dependency in asar.

[carterbs]

This is technically a vulnerability that can be ignored for this module, as electron-winstaller doesn't use any of the functionality provided by the transitive dependency in asar.

Hey Mark. Thanks for the note. I could possibly sell that. I would so much rather not have to. :-) Thank you for submitting this PR, and for getting an update for packager pushed out so quickly.

[malept]

Ugh. This module requires Node 4, and asar requires Node 6. I guess we're major version bumping. Might as well do some cleanup while we're doing that.