Mousetrap as dependency (not devDependency)

[Mitiryl]

Mousetrap is needed to load library so it should be put as dependency and not as devDependency.

[aramando]

@Mitiryl Mousetrap is bundled into the angular-hotkeys library, so users of the package don't need it as a separate dependency. It's only required for those wishing to produce new builds of the angular-hotkeys library, so devDependencies is the correct place for it.