Reverted back to snake_cased attribute from camelCased as server expects...

As per **Pivotal Story ID:** 50870361

**Root Cause:** Someone changes the property <code>custom_headers</code> to <code>customHeaders</code> in the params hash and now as the server couldn't find that value it was throwing the error during export
**Resolution:** reverted back that change
**Verification Process:** You can successfully export now