Add \n at the end of samples/local.conf

Currently if you `cat` the file, the bash prompt will be at a weird
position. And if you programmaticaly add a new line to this file,
the line will be, in fact, appended to the previous line.

Change-Id: I19ba018d9a934f8fdc07cc9bec50a0105f2710f9
diff --git a/samples/local.conf b/samples/local.conf
index e4052c2..63000b6 100644
--- a/samples/local.conf
+++ b/samples/local.conf
@@ -98,4 +98,4 @@
 # -------
 
 # Install the tempest test suite
-enable_service tempest
\ No newline at end of file
+enable_service tempest