Create CrackDataSampler

closes #4377
This is a new VectorPostprocessor that outputs fracture domain integrals for points
along a crack front, with their angular positions used for the "id" field.
I actually tried to use a range-checked parameter here, but got an error that the value was out of bounds if the user didn't specify a value.  I tried replicating that behavior elsewhere to submit a bug report on that issue, but it seems to only happen here.  I need the functionality provided by this commit now, so I plan to address that later.