pitzDaily tutorials: updated blockMeshDict files to use multi-grading

The pitzDaily case uses a lot of mesh grading close to walls and the shear layer.
Prior to v2.4, blockMesh only permitted grading in one direction within a single block,
so the pitzDaily mesh comprised of 13 blocks to accommodate the complex grading pattern.

blockMesh has multi-grading that allows users to divide a block in a given direction and
apply different grading within each division.  The mesh generated with blockMesh using
13 blocks has been replaced with a mesh of 5 blocks that use multi-grading.  The new
blockMeshDict configuration produces a mesh very similar to the original 13-block mesh.