BUG: Remove const_cast wherever that was possible

Based on some new changes to ITKv4, we can avoid using const_cast in
many places in ANTs. Therefore, I updated the ITK tag, and I removed
const_cast from everywhere that it could be avoided.
BUG: Update Baselines for three failed tests

After updating the ITK tag, 3 tests of ANTs are failed due to the
neglectable computatational difference between the baselines and test files.

The old baselines are replaced by the new files, and all tests are passed
succesfully now.
Merge pull request #95 from aghayoor/removeConstCast_r

Update ITK tag, and remove const_cast wherever possible