Update to break tar into library and utility

Cargo.toml

@@ -27,6 +27,7 @@ members = [
     "libs/ransid",
     "libs/same-file",
     "libs/syscall",
+    "libs/tar",
     "libs/termion",
     "programs/acid",
     "programs/binutils",
@@ -41,7 +42,6 @@ members = [
     "programs/pkgutils",
     "programs/smith",
     "programs/sodium",
-    "programs/tar",
     "programs/timeout",
     "programs/userutils",
     "schemes/ethernetd",
@@ -68,4 +68,5 @@ members = [
 "redox_event:0.1.0" = { path = "libs/event" }
 "redox_syscall:0.1.17" = { path = "libs/syscall" }
 "same-file:0.1.2" = { path = "libs/same-file" }
+"tar:0.4.11" = { path = "libs/tar" }
 "termion:1.3.0" = { path = "libs/termion" }