version to `1.0.0.rc2

* handling reworks (#33)
 * only output status info if both the version and source are not empty
 * have rb print the status if no args are given
 * move global .ruby-version file to `"$RB_HOME_DIR"`
 * fix for a bug in looking up the parent .ruby-version file
 * rework handling when a command line version is specified