Support SMS verification

[chpapa]

Description

Handle the use case of User Profile have an phone field, and users need to verify by SMS before using certain functions.

Related with #19 Login by SMS?

Design/Specification

• Support Twillio as the only SMS gateway is acceptable.
• Workflow:
  • Call sendSMSVerification() from client side (support any fields or a default field for phone no?)
  • Call verifySMSVerification(code) from client side, return success or failure
  • User.verifiedBySMS() return true or false

Related Issues

• Server Issues
• Client Issues
• Guides Issues

Progress Tracker

• [ ] Specification Design Approval
• [ ] Write (code + tests + API docs) then get them merged. Put All PR there
  • [ ] Code
  • [ ] Minimal tests
  • [ ] Minimal API Docs
• [ ] Guides. Put All PR there
• [ ] Release
  • [ ] Update release notes
  • [ ] Release

Advice

• Specification Design Approval
  • Once you get LGTM from another Skygear Core Team Member, you can check this checkbox. And apply the "workflow/design-complete" label.
• Coding
  • Use as many PRs as you need. Write tests in the same or different PRs, as is convenient for you.
  • API doc should goes in the same PR with the code.
  • As each PR is merged, add a comment to this issue referencing the PRs.
  • When you are done with the code, apply the "workflow/code-complete" label.
• Guides
  • Write or modify guides and get them merged in https://github.com/skygeario/guides
  • When the PR of guides is merged, check this checkbox and apply the "workflow/guides-complete" label.

[chpapa]

Code completed, guides and portal will be done in #200