Integration of astropy.units in sunpy codebase

Attempt to integrate the astropy.units into sunpy. Every function that were taking or giving a quantity now must have astropy quantity associated with them. Please tell me if I have made mistakes anywhere, or if it could be done in better way, I will make changes! 
Thank you!   
Again, we would not need to convert to radians.  Also, as above, I doubt we can obtain an angle from a cosine of an angle.
[Wikipedia]() shows this other equation
```python
declination = np.arcsin( np.sin(ob) * np.sin(true_long))
```
ping @ehsteve