Update default heroku prebuild script to lock in ARCLI version

Author: jdillick

package.json

@@ -11,7 +11,7 @@
     "build:babel-core": "cross-env NODE_ENV=production babel .core --out-dir build/.core",
     "build:babel-reactium_modules": "cross-env NODE_ENV=production babel reactium_modules --out-dir build/reactium_modules",
     "build:babel-src": "cross-env NODE_ENV=production babel src --out-dir build/src --copy-files",
-    "heroku-prebuild": "npx -p @atomic-reactor/cli arcli install",
+    "heroku-prebuild": "npx -p @atomic-reactor/cli@2.2.77 arcli install",
     "static": "npm-run-all build:* && gulp static",
     "local": "gulp local",
     "local:ssr": "gulp local:ssr",