Change ArrayContainerControl to Storage.

After a talk with Robert Maynard, we decided to change the name
ArrayContainerControl to Storage. There are several reasons for this
change.

1. The name ArrayContainerControl is unwieldy. It is long, hard for
humans to parse, and makes for long lines and wraparound. It is also
hard to distinguish from other names like ArrayHandleFoo and
ArrayExecutionManager.

2. The word container is getting overloaded. For example, there is a
SimplePolymorphicContainer. Container is being used for an object that
literally acts like a container for data. This class really manages
data.

3. The data does not necessarily have to be on the control side.
Implicit containers store the data nowhere. Derivative containers might
have all the real data on the execution side. It is possible in the
future to have storage on the execution environment instead of the
control (think interfacing with a simulator on the GPU).

Storage is not a perfect word (what does implicit storage really mean?),
but its the best English word we came up with.
Merge branch 'container-to-storage'