Moving phylogenies to society results page

Fix for #156 , #165 , #166 

'Tree' tab - with dropdown box allowing users to choose a tree.
Multiple cultural traits / environmental variables mapped onto the tree and displayed in the legend.
Newick strings stored in LanguageTree model and returned with language trees, eliminating one round trip to server.

To do:
- environmental variable scale in legend
- make missing data white
- legend issues: when many variables selected, legend is extremely long.  Will address this in the future.
- some trees have empty marker columns (e.g. 'C2' column is completely empty) when no societies on that tree have codes for that particular variables (but other societies on other trees do, hence why 'C2' is displayed as a marker column header).  Need to figure out how to remove the 'C2' header from the tree.