v0.6.0: Area 51 👽

• 💖 More robust health calculation formula (#175)
• 📈 Analytics: new routes for time-based stats (#155, #54)
• ⚖️ Ability to update impression price dynamically, allowing real-time header bidding (#166, #16)
• Pruning of unnecessary validator messages, which improves performance (#89, #165)
• Ability to pause channels/campaigns (#166, #159)
• Statistics by ad unit (#177)
• Pay event, allowing the channel creator to arbitrarily pay anyone; this allows unhealthy channels to "catch up" and regain health (#176)