Make release command run build command first

Author: rdmurphy

package.json

@@ -17,6 +17,7 @@
     "build:babel": "babel-node --extensions \".ts\" src/cli.ts \"src/{cli,index}.ts\" --target=8 --output=dist --compress",
     "build:self": "node dist/cli.js \"src/{cli,index}.ts\" --target=8 --output=dist --compress",
     "build:types": "tsc --emitDeclarationOnly --outdir types --declaration --allowSyntheticDefaultImports src/{cli,index}.ts",
+    "prerelease": "npm run build",
     "release": "np",
     "test": "echo \"Error: no test specified\" && exit 0"
   },