Stops modifying NextGenListResource @path ivar.
Stops modifying NextGenListResource @path ivar.

I'm not sure if this is necessarily the best way to do this right now, but it mirrors the behaviour in `Twilio::REST::Client` so is at least safe. The issue is that the path variable passed from the `NextGenListResource` to the `TaskRouterClient#get` method was being modified which altered it in the class. This lead to parameters being piled onto the end of an ever growing `@path` variable as more calls were made to `list`.

mypizza/twilio-ruby-private,imranraja85/twilio-ruby,xeron/twilio-ruby,philnash/twilio-ruby,jarodreyes/twilio-ruby,eloyesp/twilio-ruby,ashleydonohoe/twilio-ruby,hzchirs/twilio-ruby,dddaisuke/twilio-ruby,MadBomber/twilio-ruby,sai43/twilio-ruby,dattyle/twilio-ruby,ShanaLMoore/Magic-8-text,twilio/twilio-ruby