Remove ES5 IntelliSense Option For NTVS 1.3

[mjbvz]

Problem
Now that NTVS 1.2 has been out for a few months, we have not seen many users moving back to the old ES5 IntelliSense. However, we still support switching IntelliSense levels in the NTVS options. There are few reasons to ever do this.

Proposal
I propose we eliminate the option to switch the intellisense back to es5 entirely. Es5 IntelliSense is buggy, unstable, and does not support modern JavaScript.

Longer term, we will also eliminate this ES5 IntelliSense code, but it still currently powers the Interactive window.