Reciprocal space

Added function to nsls2/recip.py taken parts from the pyspec 

def process_to_q - This will procees the given images (certain scan) of
    the full set into receiprocal(Q) space, (Qx, Qy, Qz, I)
def process_grid  -This function will process the set of
    (Qx, Qy, Qz, I) values and grid the data
def get-grid_mesh - This function returns the X,Y, Z co-ordinates of the grid as 3d arrays
Could you add those papers to the docstring?  See sections 9 and 10 of https://github.com/numpy/numpy/blob/master/doc/HOWTO_DOCUMENT.rst.txt

Something like

```
Notes
-----
text text [1]_ some other text [2]_

.. [1]  J. Appl. Cryst. (1993). 26, 706-716 [ doi:10.1107/S0021889893004868 ] Angle calculations for a six-circle surface X-ray diffractometer M. Lohmeier and E. Vlieg

.. [2] J. Appl. Cryst. (1987). 20, 330-337 Angle Calculations for a Five-Circle Diffraetometer Used for Surface X-ray Diffraction by E. Vlieg et al.
```

You should build the documentation to make sure that this formats correctly (see http://nsls-ii.github.io/NSLS2/resource/dev_guide/doc_doc.html for how to build the docs).