rename executable to simply weberizer

I'm a stickler for good simple names and don't see why the executable
shouldn't be named simply `weberizer`. Only issue I see is that now
the filename is different from the final executable name, which can be
a bit confusing because you won't know that without reading the _oasis
file. But I still think this is better.

_oasis

@@ -15,7 +15,7 @@ Library weberizer
   Modules:        Weberizer
   BuildDepends:   netstring, str
 
-Executable weberizer_compile
+Executable weberizer
   Path:           src/
   MainIs:         weberizer_compile.ml
   BuildDepends:   weberizer