Port in optional JWAT ResourceStore

[egh]

[egh]

Does anybody have a better description for this?

[ikreymer]

I've added a simpler implementation of JWAT resource store using the FlexResourceStore as the basis.
The implementation is here:
https://github.com/iipc/openwayback/blob/master/wayback-core/src/main/java/org/archive/wayback/resourcestore/jwat/JWATFlexResourceStore.java

The jwat dependencies have already been added to wayback-core, so this resource store can be used to load using the JWAT library.

[egh]

So, this has been done. Great! Thanks, Ilya.