Pushes all map functionality up to Base

[jwittenbach]

No description provided.

[jwittenbach]

@freeman-lab This was something that I had mentioned doing a while back. It came up presently because I wanted the value_shape argument in map to avoid the shape/dtype check in thunder-regression. However, it wasn't actually exposed on Series and was exposed by a different name (dims) on Images. So I figured I might as well just do it.

The only thing that is slightly awkward is that you can now no longer set the index for Series during the map, since that doesn't extend to Images. I handled this by replacing all instances with the pattern:

return series.map(f, index=index)

with

result = series.map(f)
result.index = index
return result

which doesn't seem so bad.

[jwittenbach]

After offline conversation with @freeman-lab, decided to solve this in a slightly different fashion: #337