[Android] Refine the URI scheme Job Factory usage

Mark the Job Factory usage more clearly with three steps:
    1, Add default schemes(http, ftp etc)
    2, Add new basic schemes(data, file, app)
    3, Add scheme interceptors(content, file asset)

Add the request interceptor to handle the shouldInterceptRequest
API for embedder.

BUG=https://crosswalk-project.org/jira/browse/XWALK-655