Upgrading ITK superbuild to ITK 4.4.0

Change-Id: I2bad11fc47c83cf5da230935df788ce45742864c
Merge topic 'SIMPLEITK-400_UpgradeTowardsITK_4.4' into next

482712b Upgrading ITK superbuild to ITK 4.4.0
Merge topic 'FixWriterArgumentByName'

73120d0 Remove in prefix from write function argument
Merge topic 'FixMaskedFFTNormXCorrTolerance'

968db94 Fix tolerance for FFTW
Merge branch 'master' into next

Change-Id: I24b9455fd6dc8f3c2c21bef6428485fedfa3f0f5