Improved built JS compat w/ CloudFlare Auto Minify (#861)
Improved built JS compat w/ CloudFlare Auto Minify (#861)

refs TryGhost/Ghost#8815, TryGhost/Ghost#8840, TryGhost/Ghost#8842, TryGhost/Ghost#8849
- `ember-cli` 2.14 introduced some [new defaults for uglify-js](https://github.com/ember-cli/ember-cli/pull/7077) that resulted in CloudFlare's Auto Minify feature mangling the JS files and causing syntax errors
- revert the `semicolons: false` option to restore compatibility

**Note:** This does _not_ mean it's recommended to use CloudFlare's Auto Minify feature. It's still recommended that all CloudFlare's performance settings are [disabled for /ghost* URLs](https://docs.ghost.org/docs/troubleshooting#section-ghost-admin-not-loading)
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