Configurable copyright string for installer executable

[bostondv]

The Copyright string in the installer exe details is "Copyright (C) 2014" and appears it can't be edited unless using rcedit after the installer is generated.

I'd suggest using the package.json "license" value like it does with other details for the installer executable.

[ldd]

I hate doing this but... +1 (Not that the year of copyright has any bearing on keeping copyright, but it looks better)

[anaisbetts]

@bostondv Not a bad idea, I'd take a PR for that