Support Chai 3.x

Fixes #65. Also tests against all supported Chai versions.

package.json

@@ -18,16 +18,19 @@
     "lib"
   ],
   "scripts": {
-    "test": "mocha",
+    "test": "npm run test-chai-1-9-2 && npm run test-chai-2-3-0 && npm run test-chai-3-0-0",
+    "test-chai-1-9-2": "npm install [email protected] && mocha",
+    "test-chai-2-3-0": "npm install [email protected] && mocha",
+    "test-chai-3-0-0": "npm install [email protected] && mocha",
     "lint": "jshint ./lib",
     "cover": "istanbul cover node_modules/mocha/bin/_mocha && opener ./coverage/lcov-report/lib/sinon-chai.js.html"
   },
   "peerDependencies": {
-    "chai": ">=1.9.2 <3",
+    "chai": ">=1.9.2 <4",
     "sinon": ">=1.4.0 <2"
   },
   "devDependencies": {
-    "chai": "^1.9.2",
+    "chai": "^3.0.0",
     "coffee-script": "~1.8.0",
     "istanbul": "~0.3.2",
     "jshint": "^2.5.6",