Accept endpoint with or without trailing slash

[rickmak]

We are accepting https://myapp.skygeario.com/ but not https://myapp.skygeario.com.

• Skygear SDK Date/Version: v0.1.0
• JS runtime: node
• Skygear Server Date/Version:
• [ ] Is this a regression?
• [ ] Attached logs, screenshots

Expected Results

We are accepting both https://myapp.skygeario.com/ and https://myapp.skygeario.com.