Clean up shebang warnings (ros-infrastructure#630)

Two classes of changes here:
1. `catkin_support.py` is executable, but has no shebang, so I removed
the executable bit.
2. `main.py` has a shebang and `__main__` handler, and I removed it. It
can still be executed directly using the python executable, but like
with ros-infrastructure/rospkg#159, it doesn't make sense to have
executable scripts in the module.

src/rosdep2/main.py

@@ -1,4 +1,3 @@
-#!/usr/bin/env python
 # Copyright (c) 2009, Willow Garage, Inc.
 # All rights reserved.
 #

src/rosdep2/platforms/arch.py

@@ -1,4 +1,3 @@
-#!/usr/bin/env python
 # Copyright (c) 2009, Willow Garage, Inc.
 # All rights reserved.
 #

src/rosdep2/platforms/cygwin.py

@@ -1,4 +1,3 @@
-#!/usr/bin/env python
 # Copyright (c) 2009, Willow Garage, Inc.
 # All rights reserved.
 #

src/rosdep2/platforms/debian.py

@@ -1,4 +1,3 @@
-#!/usr/bin/env python
 # Copyright (c) 2009, Willow Garage, Inc.
 # All rights reserved.
 #

src/rosdep2/platforms/freebsd.py

@@ -1,4 +1,3 @@
-#!/usr/bin/env python
 # Copyright (c) 2010, Willow Garage, Inc.
 # All rights reserved.
 #

src/rosdep2/platforms/gem.py

@@ -1,4 +1,3 @@
-#!/usr/bin/env python
 # Copyright (c) 2009, Willow Garage, Inc.
 # Copyright (c) 2012, Intermodalics, BVBA.
 # All rights reserved.

src/rosdep2/platforms/gentoo.py

@@ -1,4 +1,3 @@
-#!/usr/bin/env python
 # Copyright (c) 2009, Willow Garage, Inc.
 # All rights reserved.
 #

src/rosdep2/platforms/osx.py

@@ -1,4 +1,3 @@
-#!/usr/bin/env python
 # Copyright (c) 2009, Willow Garage, Inc.
 # All rights reserved.
 #

src/rosdep2/platforms/pip.py

@@ -1,4 +1,3 @@
-#!/usr/bin/env python
 # Copyright (c) 2009, Willow Garage, Inc.
 # All rights reserved.
 #

src/rosdep2/platforms/redhat.py

@@ -1,4 +1,3 @@
-#!/usr/bin/env python
 # Copyright (c) 2009, Willow Garage, Inc.
 # All rights reserved.
 #

src/rosdep2/platforms/slackware.py

@@ -1,4 +1,3 @@
-#!/usr/bin/env python
 # Copyright (c) 2009, Willow Garage, Inc.
 # All rights reserved.
 #