Loki: Creation policies

# Creation policies
[Cached Factory]

Defines a way to limit the creation operation. More...

Collaboration diagram for Creation policies:

## Classes
class | Loki::NeverCreate
| Never allows creation. Testing purposes only. More...
class | Loki::AlwaysCreate
| Always allows creation. More...
class | Loki::RateLimitedCreation
| Limit in rate. More...
class | Loki::AmountLimitedCreation
| Limit by number of objects. More...

## Detailed Description

Defines a way to limit the creation operation.

For instance one may want to be alerted (Exception) when

- Cache has created a more than X object within the last x seconds
- Cache creation rate has increased dramatically

which may result from bad caching strategy, or critical overload