pass function to dimension constructor

[mikeAdamss]

can we add an apply method to databaker dimension constructors, eg:

HDim(cells, "My Dim", CLOSEST, ABOVE, apply=my_function)

or even

HDim(cells, "My Dim", CLOSEST, ABOVE, apply=lambda x: x.strip())

So basically a databaker parallel of the pandas apply() function. I think it's both possible and relatively trivial and would allow us to make any string changes upstream (i.e before we pivot) which should be super efficient.

[mikeAdamss]

yeah was easy, have put it in pr: #28

[mikeAdamss]

did it