TACHYON-198 Move UserConf usage to use TachyonConf

This PR consist next steps to integrate new configuration work:
-) Remove usage of UserConf
-) Push TachyonConf to Tachyon Hadoop's file system (aka TFS class).
-) Remove UserConf.java from repo.
if our usage is a int, then why do we expect that this value is a long?

Also, why is it calling `getBytes`? Shouldn't that be a `byte[]`? Thats what the code reads like