add maths.MaxImage for fslmaths -Tmax option
test maths.MaxImage for fslmaths -Tmax option
added maths.MaxImage examples
Merge pull request #512 from nicholsn/enh/MathsMaxImage

Enh/maths max image
Merge branch 'master' into nipy/trim

* master:
  added maths.MaxImage examples
  test maths.MaxImage for fslmaths -Tmax option
  add maths.MaxImage for fslmaths -Tmax option