Milestone: budget control & nodes config in yaml

[mateuszsrebrny]

Why

• give users the control over the cluster and the costs

How

• simple budget control mechanism definable in cluster yaml
• simple node definition mechanism definable in cluster yaml

Tasks

Beta Give feedback

1. glm per hour limit in cluster yaml
2. simple heuristics when to not start new nodes when limit would be endangered
3. simple definition of node types in cluster yaml
4. status in golem-ray showing current spendings
5. forecast of spending for the next period of time (5 mins? 15 mins?)
6. allow new nodes when forecast is under the limit
7. stop existing nodes when forecast is over the limit

[mateuszsrebrny]

cleaning issues (issue no longer needed)