Merge bytebuffer and memory stores into a single memory store options

[kimchy]

The bytebuffer store name is really bad. It basically exposes the user to the internals of Java on how a direct memory allocation (outside the JVM heap) is done.

Instead, there should be a single memory store, with the option to choose its "location", which can be either "heap" or "direct", with "direct" being the default.

This does mean that if someone was configuring to use the bytebuffer, things will break and they will need to change to memory type.

[kimchy]

Merge bytebuffer and memory stores into a single memory store options, closed by 8727815.