XiChen

@dbw9580 The URI created by Alluxio we may be able to restrict the path to not have `%` in it. But if `%` is in the UFS, this bug will...

So we can remove the percent-encoding deal from the `alluxio.util.URIUtils#hash`, and make it consistent with `AlluxioURI.normalizePat`?

## **Phenomenon** ``` Error: 3.863 [ERROR] alluxio.AlluxioURITest.joinUnsafe Time elapsed: 0.008 s