add emacs shell-script tagging

for files that don't start with a #! or end in .sh, the added tags
are nice for emacs users to automatically switch to the right mode.

Change-Id: If4b93e106191bc744ccad8420cef20e751cdf902
diff --git a/lib/tls b/lib/tls
index 202edef..fb8f4b9 100644
--- a/lib/tls
+++ b/lib/tls
@@ -316,3 +316,7 @@
 
     stud $STUD_PROTO -f $f_host,$f_port -b $b_host,$b_port $DEVSTACK_CERT 2>/dev/null
 }
+
+# Local variables:
+# mode: shell-script
+# End: