clean-up trailing whitespace (#453)

These changes have been mostly auto-generated with:

	find . -type f -print0 | xargs -0 perl -pi -e 's/ +$//'

Signed-off-by: Radostin Stoyanov <rstoyanov@fedoraproject.org>

exercises/basic/triangle-topo/topology.json

@@ -16,7 +16,7 @@
         "s3": { "runtime_json" : "triangle-topo/s3-runtime.json" }
     },
     "links": [
-        ["h1", "s1-p1"], ["s1-p2", "s2-p2"], ["s1-p3", "s3-p2"], 
+        ["h1", "s1-p1"], ["s1-p2", "s2-p2"], ["s1-p3", "s3-p2"],
         ["s3-p3", "s2-p3"], ["h2", "s2-p1"], ["h3", "s3-p1"]
     ]
 }