tslint: Enable no-var-requires

Rationale from the rule's page:

AMD-style require([]) and CommonJS-style require("") statements are
environment-specific and more difficult to statically analyze.

ES2015-style imports are part of the JavaScript language specfication
and recommended as the path going forward. TypeScript will compile them
to environment-specific forms as needed.

tslint.json

@@ -26,7 +26,6 @@
 		"no-shadowed-variable": false,
 		"no-trailing-whitespace": false,
 		"no-unnecessary-initializer": false,
-		"no-var-requires": false,
 		"object-literal-shorthand": false,
 		"object-literal-sort-keys": false,
 		"one-line": false,