[changed] DropdownButton, SplitButton, DropdownMenu, MenuItem completely rewritten

Adds:
- Keyboard Navigation
- Aria properties for Assistive Technology
- Option to use custom menu with any of the dropdown variations
- `NavDropdown` component (Similar to `DropdownButton` but specifically
  for use within `Nav` components.
- `DropdownToggle` Component which can be used as an alternative to the
  `DropdownButton` `title` prop. Can either be directly imported or used
  as a static property of the `DropdownButton` with
  `DropdownButton.Toggle`. _(Useful should you want to use glyphicons or
  custom html within the toggle that's not a simple string.)_
- `SplitToggle` Similar to the `DropdownToggle` but targeted at the
  `SplitButton`'s toggle.
- Generic `Dropdown` component for easy dropdown customization.

Changed:
- Event handling of all these components to be in line with react-bootstrap#419
- Written with ES6 class syntax

Removed:
- DropdownStateMixin - Everything is using ES6 class syntax so no more
  mixin usage

Author: mtscout6

.ackrc

@@ -1,3 +1,4 @@
+--ignore-dir=.coverage
 --ignore-dir=lib
 --ignore-dir=dist
 --ignore-dir=amd
@@ -7,3 +8,4 @@
 --ignore-dir=tmp-bower-repo
 --ignore-file=match:test_bundle.js
 --ignore-file=match:components.html
+--ignore-file=match:.orig

.eslintrc

@@ -10,7 +10,8 @@
   "parser": "babel-eslint",
   "plugins": [
     "react",
-    "babel"
+    "babel",
+    "lodash"
   ],
   "rules": {
     "constructor-super": 2,
@@ -32,11 +33,12 @@
     "react/no-did-mount-set-state": 2,
     "react/no-did-update-set-state": 2,
     "react/no-multi-comp": 2,
-    "react/prop-types": [2, { "ignore": [ "children", "className" ] }],
+    "react/prop-types": [1, { "ignore": [ "children", "className" ] }],
     "react/react-in-jsx-scope": 2,
     "react/self-closing-comp": 2,
     "react/wrap-multilines": 2,
     "react/jsx-uses-vars": 2,
+    "lodash/import": 2,
     "space-infix-ops": 2,
     "strict": [2, "never"]
   }