chore(): use typescript 1.7 for now

1.8 breaks a few things, use 1.7 until we figure them out

gulpfile.js

@@ -31,7 +31,8 @@ function getTscOptions(name) {
     experimentalDecorators: true,
     target: "es5",
     module: "commonjs",
-    isolatedModules: true
+    isolatedModules: true,
+    typescript: require('typescript')
   }
 
   if (name === "typecheck") {

package.json

@@ -78,7 +78,7 @@
     "strip-sourcemap-loader": "0.0.1",
     "systemjs": "0.19.6",
     "through2": "^0.6.3",
-    "typescript": "^1.7.3",
+    "typescript": "1.7.5",
     "vinyl": "^0.4.6",
     "webpack": "^1.12.2",
     "yargs": "^3.6.0"