lib: Add new tst_device for shell

The motivation is to have a single place where we handle device
creation/deletion.

Signed-off-by: Cyril Hrubis <chrubis@suse.cz>
Acked-by: Jan Stancek <jstancek@redhat.com>
diff --git a/testcases/lib/.gitignore b/testcases/lib/.gitignore
index 77acb57..920817c 100644
--- a/testcases/lib/.gitignore
+++ b/testcases/lib/.gitignore
@@ -3,3 +3,4 @@
 tst_checkpoint
 tst_rod
 tst_kvcmp
+tst_device