Loosen MySQL permissions in developer docs
Loosen MySQL permissions in developer docs

While following the instructions provided by this document, I encountered the following errors:
```
➜  orchestrator git:(master) ✗ go run go/cmd/orchestrator/main.go http
2018-08-29 13:35:07 ERROR Error 1045: Access denied for user 'orchestrator'@'172.23.0.1' (using password: YES)
2018-08-29 13:35:07 DEBUG Connected to orchestrator backend: orchestrator:?@tcp(127.0.0.1:43306)/orchestrator?timeout=1s
2018-08-29 13:35:07 DEBUG Orchestrator pool SetMaxOpenConns: 128
2018-08-29 13:35:07 DEBUG Initializing orchestrator
2018-08-29 13:35:07 DEBUG Migrating database schema
2018-08-29 13:35:07 FATAL Error 1045: Access denied for user 'orchestrator'@'172.23.0.1' (using password: YES)
```

This is likely because I was using a MySQL backend hosted in docker.

I propose we change the grants to be more permissive to ease onboarding developers.
github/orchestrator,github/orchestrator,github/orchestrator,github/orchestrator