gscam_nodelet.h: include scoped_ptr.hpp to compile with boost 1.57

When compiling gscam with the currently latest boost version 1.57,
it fails with:
In file included from [...]/src/gscam_nodelet.cpp:5:0:
[...]/include/gscam/gscam_nodelet.h:20:12: error: 'scoped_ptr' in namespace 'boost' does not name a template type
     boost::scoped_ptr<GSCam> gscam_driver_;
            ^
[...]/include/gscam/gscam_nodelet.h:21:12: error: 'scoped_ptr' in namespace 'boost' does not name a template type
     boost::scoped_ptr<boost::thread> stream_thread_;
            ^

It seems that the dependencies of boost/thread.hpp have changed
and boost/scoped_ptr.hpp is not included anymore with
boost/thread.hpp. Hence, the scoped_ptr is not defined in the
gscam_nodelet header. After scanning quickly through the release
notes of version 1.57, the boost bug tracker and a few changesets,
I could not find not a hint what has changed in the thread library
that gscam must include scoped_ptr itself.

This commit simply addresses the compiler error by explicitly
adding boost's scoped_ptr header in the gscam_nodelet header.
As this commit also compiles with boost version 1.56, the commit
is not expected to cause any problems with other build
configurations.

Signed-off-by: Lukas Bulwahn <[email protected]>

include/gscam/gscam_nodelet.h

@@ -6,6 +6,7 @@
 #include <gscam/gscam.h>
 
 #include <boost/thread.hpp>
+#include <boost/scoped_ptr.hpp>
 
 namespace gscam {
   class GSCamNodelet : public nodelet::Nodelet