Add dynamic pair-list pruning framework

Add dynamic pair-list pruning framework

The change add the logistic for setting up dynamic pruning of the
nbnxn pair-lists. Dynamic pruning allows for an increase in nstlist
and rlist while computing fewer pair interactions in the non-bonded
kernel. This comes at the cost of running an extra pruning kernel
every few steps and added communication due to larger buffers.

The kernels, documentation and heuristic for choosing nstlist
will be added in separate changes.

Change-Id: Id8040b95f812df60f117279267bf551ff4ac8d79