Update the species edit row with species name.

We want the user to know that his/her choice was respected when editing the tree
details and changing the speices. To do this we add the current species to the
table cell and update it when a new species is selected. This requires making
the tree detail view a delegate for data coming from selected rows on the
species table view controller.
Add section labels to tree edit screen.

We want users to know what the fields they are editing are related to in
reference to the tree detail screen. We had labels for the sections on the
detail screen but not the edit screen so we add them here by reshuffling the
same labels that are used on the edit screen.
Species selection returns scientific name.

The species selection already returned a common name to the delegate but did not
return the scientific name. To provide more flexability for the future we add
the scientific name as well. Where we use this value and update the cell in the
tree detail view, we split out the magic string update code to a separeate
method on the OTMTreeDetailViewController to make it easier to deal with
updating this cell in other places in the code.
Comments to identify magic numbers & array indexes.

Call attention to the use of hard coded special numbers with @MAGIC annotation.
Also clean up some white space.