Fixed compilation of IECoreAppleseed on OS X.

Without constructing the pointer separately, GCC 4.2.1 was giving the following error :

contrib/IECoreAppleseed/src/IECoreAppleseed/bindings/ToAppleseedConverterBinding.cpp:59: error: no matching function for call to 'foundation::auto_release_ptr<renderer::Entity>::auto_release_ptr(foundation::auto_release_ptr<renderer::Entity>)'
Fixed linking of IECoreAppleseed module on OS X.
Added crop window support for appleseed
Merge pull request #364 from appleseedhq/appleseed_crop_window

Added crop window support for appleseed
Merge pull request #363 from johnhaddon/appleseedOSXFixes

Appleseed OS X fixes
Added appleseed lib path to IECoreAppleseed python module env.
fixed maya sceneshape component selection bug
Merge pull request #365 from appleseedhq/appleseed_linux_build_fix

appleseed linux build fix
Merge pull request #366 from davidsminor/mayaGlSelectionFix

fixed maya sceneshape component selection bug
fixed crash when expanding ieSceneShapes containing coordinate systems
Merge pull request #367 from davidsminor/locatorComputeFix

fixed crash when expanding ieSceneShapes containing coordinate systems