Group CLI demo into subdirectory. (#6258)

CLI is not most developed interface. Putting them into correct directory can help new users to avoid it as most of the use cases are from a language binding.

demo/CLI/yearpredMSD/csv2libsvm.py

@@ -0,0 +1,9 @@
+import sys
+fo = open(sys.argv[2], 'w')
+
+for l in open(sys.argv[1]):
+    arr = l.split(',')
+    fo.write('%s' % arr[0])
+    for i in range(len(arr) - 1):
+        fo.write(' %d:%s' % (i, arr[i+1]))
+fo.close()