Add TypeScript declarations to prism-element. (#39)

* Add type declaration generation config.
* Generate minimal package.json from bower.json
* Update and/or configure type declarations.

.gitignore

@@ -1,2 +1,3 @@
 bower_components*
 bower-*.json
+node_modules

.travis.yml

@@ -12,6 +12,10 @@ addons:
 before_script:
   - npm install -g polymer-cli
   - polymer install --variants
+  - >-
+    npm run update-types && git diff --exit-code || (echo -e
+    '\n\033[31mERROR:\033[0m Typings are stale. Please run "npm run
+    update-types".' && false)
 script:
   - xvfb-run polymer test
   - >-

gen-tsd.json

@@ -0,0 +1,9 @@
+{
+  "removeReferences": [
+    "../prism/prism.d.ts",
+    "../prism/themes/prism.d.ts"
+  ],
+  "renameTypes": {
+    "Prism.Lang": "{}"
+  }
+}