Add routes

Users

• GET /user
• POST /user
• GET /user/?user_id/accounts
• GET /user/?user_id/entities
• GET /user/?user_id/labels
• GET /user/?user_id/transactions

Accounts

• POST /account
• GET /account/?account_id
• PUT /account/?account_id
• DELETE /account/?account_id
• GET /account/?account_id/labels
• GET /account/?account_id/transactions

Entities

• POST /entity
• PUT /entity
• DELETE /entity

Labels

• POST /label
• PUT /label
• DELETE /label

Transactions

• POST /expense
• GET /expense/?transaction_id
• PUT /expense/?transaction_id
• DELETE /expense/?transaction_id
• POST /income
• GET /income/?transaction_id
• PUT /income/?transaction_id
• DELETE /income/?transaction_id
• POST /transfer
• GET /transfer/?transaction_id
• PUT /transfer/?transaction_id
• DELETE /transfer/?transaction_id