Base implementation of matching service

[bachletuankhai]

Basic functionality for matching service, including:

• Client connection via socket.io
• Match request queues
• Matching users based on topic and difficulty (hard match only, i.e. users only match with ppl of same difficulty and topic)
• Match cancel (not really tested)

Pending items:

1. Persisting of tickets on external database
2. Validation of ticket and user states
3. Authentication upon initial connection