Fix: Typings dependencies

Typings dependencies are now installable with
`typings install:chai-iterator`. The "chai" module is imported at the
top of the declarations file and the README has been updated
accordingly.

Author: mcmath

README.md

@@ -200,11 +200,11 @@ function will also be available globally as `chaiIterator`.
 #### TypeScript
 
 [TypeScript][typescript] declarations are included in the package. To use them,
-first ensure the [npm declarations for Chai][chai-typings] are installed via
-[typings][typings].
+ensure Chai Iterator is installed with [npm][npm], then install the declarations
+and their dependencies via [typings][typings].
 
 ```sh
-typings install npm~chai --save
+typings install --save-dev npm:chai-iterator
 ```
 
 In the [compiler options][compiler-options], set `"target"` to `"es6"`, or at

chai-iterator.d.ts

@@ -1,4 +1,6 @@
-declare module "chai/lib/Assert" {
+import "chai";
+
+declare module "~chai/lib/Assert" {
 
   interface Assert {
     isIterable(val: any, msg?: string): void;
@@ -22,7 +24,7 @@ declare module "chai/lib/Assert" {
 
 }
 
-declare module "chai/lib/Assertion" {
+declare module "~chai/lib/Assertion" {
 
   interface Assertion {
     iterable: Assertion;