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.
https://tachyon.atlassian.net/browse/TACHYON-250

Put the JIRA there to talk about this. Please let your arguments there on this subject.