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.
It's your code but a MooseEnum might improve this syntax.  You could do `"X=1 Y Z"` which would allow you to read an "axis" from the user but in your code you could simply use the value as an integer. It's fine like this though if that's the way you want it.