Parameterizing Karet with respect to VDOM implementation

This is an experiment towards solving #8 and #7.

package.json

@@ -1,6 +1,6 @@
 {
   "name": "karet",
-  "version": "1.1.8",
+  "version": "2.0.0",
   "description": "Karet is a library that allows you to embed Kefir observables into React VDOM",
   "module": "dist/karet.es.js",
   "main": "dist/karet.cjs.js",
@@ -47,7 +47,10 @@
     "kefir": "^3.7.1",
     "mocha": "^3.2.0",
     "nyc": "^10.2.0",
+    "preact": "^8.1.0",
+    "preact-render-to-string": "^3.6.0",
     "prop-types": "^15.5.8",
+    "react": "^15.0.1",
     "react-addons-test-utils": "^15.5.1",
     "react-dom": "^15.5.3",
     "rollup": "^0.41.6",
@@ -58,8 +61,7 @@
     "rollup-plugin-uglify": "^1.0.1"
   },
   "dependencies": {
-    "infestines": "^0.4.4",
-    "react": "^15.0.1"
+    "infestines": "^0.4.4"
   },
   "peerDependencies": {
     "kefir": "^3.7.0"