[tests] Rework Marabou test.

tests/marabou.t

 Test verify
-  $ cat - > bin/alt-ergo << EOF
-  > #!/bin/sh
-  > echo "2.4.0"
-  > EOF
-
-  $ chmod u+x bin/alt-ergo bin/pyrat.py bin/Marabou
-
-  $ bin/alt-ergo
-  2.4.0
-
-  $ bin/pyrat.py --version
-  PyRAT 1.1
+  $ chmod u+x bin/Marabou
 
   $ bin/Marabou --version
   1.0.+