update initializer API, including: NormalInitializer, TruncatedNormalInitializer, UniformInitializer, XavierNormalInitializer, XavierUniformInitializer, NumpyArrayInitializer.

* add base name alias; test=develop

* fix embedding bug; test=develop

* fix io error; test=develop

* add metric; test=develop

* add import palce; test=develop

* add setup; test=develop

* fix incubate reader; test=develop

* fix initializer error; test=develop