[Feature] API server using Node

[li-kai]

As dictated by the progenitor @yangshun (and through much discussion) I think we might still go with node. To summarize, the benefits are

1. Newcomers know Javascript, courtesy of CS1101S
2. Our entire stack is already Javascript
3. We may be able to share code

The cons are

1. More code to write

Thankfully, I don't think there's too much code. The following are steps needed to get out api mvp out:

• [x] Remove previous data code that reads files #1105
• [x] Upgrade to apollo-server 2 #1107
• [x] Add new schemas for a fully functional server #1111
• [ ] Add queries to fetch data from db #1151
• [ ] Add mutations to add data from db
• [ ] Add validations to mutations

[taneliang]

Actually, I think a significant part of the complexity is in the auth/sync parts. That doesn't really matter if we're going to split the 2 servers, but if we're implementing them together then we need to try those early so that we get an accurate picture of what's needed and potential problems. That'll allow us to better evaluate Rails vs Node vs whatever else