IDL Generator (Prototype)

* Combined with following projects:
  (TODO: Reference and patch instead of hard copy)
  - chromium_src/tools/idl_parser/
  - chromium_src/third_party/WebKit/Source/bindings/
  - chromium_src/third_party/WebKit/Tools/Scripts/webkitpy/
  - chromium_src/third_party/jinja2/
  - chromium_src/third_party/markupsafe/
  - chromium_src/third_party/ply/

* This generator actually:
  1. Copy idl to Source/bindings/tests/idls/
  2. Call `run-bindings-tests` to read all idls
     under Source/bindings/tests/idls/
  3. Put results under Source/bindings/tests/results/
  4. Copy results(JAVA and JS files) to ninja gen dir
  See "build/idl-generator/go" for details.

* Added echo as a demo