Make button disabling work right

Two related pieces:
1) Expose inlineEditForm.enableOrDisableEditButton() so the map page can call it when you click on a tree
2) Change all of our <a class="btn"> to <button class="btn"> so they can be easily disabled. Bootstrap displays them identically.
Merge pull request #494 from RickMohr/fix-button-disabling

Fix button disabling