Adds a production build tsconfig

package.json

@@ -30,15 +30,15 @@
   },
   "scripts": {
     "precommit": "lint-staged",
-    "prepush": "npm run build",
+    "prepush": "yarn run build",
     "test": "jest",
     "test:watch": "jest --watch",
     "lint": "tslint \"source/**/*.ts\"",
     "lint:fix": "tslint \"source/**/*.ts\" --fix",
-    "prepublishOnly": "npm run build && yarn declarations",
-    "build": "shx rm -rf ./distribution && tsc && madge ./distribution --circular",
+    "prepublishOnly": "yarn run build && yarn declarations",
+    "build": "shx rm -rf ./distribution && tsc -p tsconfig.production.json && madge ./distribution --circular",
     "build:watch": "tsc -w",
-    "link": "npm run build && chmod +x distribution/commands/danger.js && npm link",
+    "link": "yarn run build && chmod +x distribution/commands/danger.js && npm link",
     "declarations": "ts-node ./scripts/create-danger-dts.ts",
     "docs:cp_defs":
       "mkdir docs/docs_generate; cp source/danger.d.ts docs/docs_generate; cp node_modules/github/lib/index.d.ts docs/docs_generate/github.d.ts",

tsconfig.production.json

@@ -0,0 +1,15 @@
+{
+  "extends": "./tsconfig.json",
+  "compilerOptions": {
+    "target": "es5"
+  },
+  "exclude": [
+    "dangerfile.ts",
+    "scripts",
+    "node_modules",
+    "source/**/fixtures/*",
+    "source/**/_tests/*",
+    "distribution",
+    "types"
+  ]
+}