Merge pull request #6 from adowns01/tree-model

added death logic for tree
grove works with the models, is not connected to view
when a new tree is added to the grove the tree shows up on DOM, but doesn't update with ageing
grove fully connected with DOM
Merge pull request #7 from adowns01/grove

added grove logic
refactored groveView
Merge pull request #8 from adowns01/grove

refactored groveView
removed constants from being stored in tree model