added Fermi and Vertical axis T0 choppers to helper.py and added Fermi Chopper and Vertical axis T0 chopper to sequoia_geometry.py
fixed file geometry pointer

fixed file geometry pointer
fixed geometry view of T0 chopper
Update helper.py

fixed misspelling in line 740
Merge pull request #60 from mantidproject/dgs_choppers

Add support for Fermi and T0 choppers.