Add support for ResourceQuota

[atantawi]

ResourceQuota

In case a ResourceQuota object exists in the namespace of an AppWrapper, the dispatcher should check if the requests and limits of the AppWrapper are satisfied by the available quota in the ResourceQuota, before the AppWrapper is dispatched and the corresponding pods are created. This avoids some (or all) pods of the AppWrapper being rejected by the resource quota admission controller.

Handling of this issue may be done in phases:

1. Basic handling of quota resources {cpu, memory, ...}, {requests.cpu, requests.memory, ...} and {limits.cpu, limits.memory, ...}, including extended resources.
2. Consideration of object count quotas count/<resource>.<group> and count/<resource>.
3. Cluster wide quotas: ClusterResourceQuota

Issues to worry about:

• If a ResourceQuota object exists in the namespace of an AppWrapper, requests and limits need to be specified at the container and AppWrapper levels.
• Accounting for used quota may get tricky! The reported Used quota in the ResourceQuota object reflects the pods that passed the quota admission controller AFTER the ResourceQuota object is created.
• Updating the quota usage as AppWrapper are dispatched from the queue, and before their pods are actually created. Should this data be kept in the Cache, or recalculated when needed?

[atantawi]

Need to handle more than one ResourceQuota object per NameSpace.

[atantawi]

Need to handle scope of ResourceQuota objects.