Remove the Python 2.4 dependency and use just 'python'

Many Linux distributions are including python2.5 by default, as
it is the latest stable release of the language.  Using python2.4
(and asking users to specifically install it) is just cruel and
unusual punishment.

Signed-off-by: Shawn O. Pearce <sop@google.com>

main.py

@@ -15,7 +15,7 @@
 # limitations under the License.
 
 magic='--calling-python-from-/bin/sh--'
-"""exec" python2.4 -E "$0" "$@" """#$magic"
+"""exec" python -E "$0" "$@" """#$magic"
 if __name__ == '__main__':
   import sys
   if sys.argv[-1] == '#%s' % magic: