Craete ResourcePackage form URI
Add method static ResourcePackage.fromURI(java.net.URI), that can create an ResourcePackage that represents a URI located local directory or JAR file (other types like directory or JAR from web is not supported).
Bug Fixes
fix #3, now invalid identifier file name will cause an exception (instead of assertion) on package initialize stage.
fix #4, package on disk will always use root directory of classpath as the root.
fix dangling jar entry may cause parse deadlock, they can be ignored normally.