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.
Because I only have one helper method to return number of bytes from properties with long as return value.
I could call getInt but properties about bytes size could be in form of 3MB or 2GB so call to TachyonConf.getBytes is used instead.