make "child-clean-exit" the default option

Fix #408. The destructor of NW Shell will try to shutdown and kill
the renderer immediately:

content::RenderProcessHostImpl::Cleanup (this=0xf683b40) at ../../content/browser/renderer_host/render_process_host_impl.cc:1159
0x0a16e614 in content::RenderProcessHostImpl::Release (this=0xf683b40, routing_id=1)
at ../../content/browser/renderer_host/render_process_host_impl.cc:1140
0x0a194d93 in content::RenderWidgetHostImpl::~RenderWidgetHostImpl (this=0xf6a2884, __vtt_parm=0xf4a5dfc, __in_chrg=<optimized out>)
at ../../content/browser/renderer_host/render_widget_host_impl.cc:203
0x0a17ac9c in content::RenderViewHostImpl::~RenderViewHostImpl (this=0xf6a2880, __in_chrg=<optimized out>, __vtt_parm=<optimized out>)
at ../../content/browser/renderer_host/render_view_host_impl.cc:199
0x0a17ad21 in content::RenderViewHostImpl::~RenderViewHostImpl (this=0xf6a2880, __in_chrg=<optimized out>, __vtt_parm=<optimized out>)
at ../../content/browser/renderer_host/render_view_host_impl.cc:215
0x0a19ac9f in content::RenderWidgetHostImpl::Destroy (this=0xf6a2884)
at ../../content/browser/renderer_host/render_widget_host_impl.cc:1375
0x0a1957bd in content::RenderWidgetHostImpl::Shutdown (this=0xf6a2884)
at ../../content/browser/renderer_host/render_widget_host_impl.cc:311
0x0a18045a in content::RenderViewHostImpl::Shutdown (this=0xf6a2880) at ../../content/browser/renderer_host/render_view_host_impl.cc:1083
0x0a39cde9 in content::RenderViewHostManager::~RenderViewHostManager (this=0xf6a1bd8, __in_chrg=<optimized out>)
at ../../content/browser/web_contents/render_view_host_manager.cc:54
0x0a1d8ab2 in content::WebContentsImpl::~WebContentsImpl (this=0xf6a1a80, __in_chrg=<optimized out>)
at ../../content/browser/web_contents/web_contents_impl.cc:328
0x0a1d8bbb in content::WebContentsImpl::~WebContentsImpl (this=0xf6a1a80, __in_chrg=<optimized out>)
at ../../content/browser/web_contents/web_contents_impl.cc:378
0x08542f36 in base::DefaultDeleter<content::WebContents>::operator() (this=0xf813a50, ptr=0xf6a1a80) at ../../base/memory/scoped_ptr.h:138
0x085426c3 in base::internal::scoped_ptr_impl<content::WebContents, base::DefaultDeleter<content::WebContents> >::~scoped_ptr_impl (this=
0xf813a50, __in_chrg=<optimized out>) at ../../base/memory/scoped_ptr.h:221
0x085424dd in scoped_ptr<content::WebContents, base::DefaultDeleter<content::WebContents> >::~scoped_ptr (this=0xf813a50,
__in_chrg=<optimized out>) at ../../base/memory/scoped_ptr.h:305
0x08540537 in content::Shell::~Shell (this=0xf813a20, __in_chrg=<optimized out>) at ../../content/nw/src/nw_shell.cc:126
0x085405c7 in content::Shell::~Shell (this=0xf813a20, __in_chrg=<optimized out>) at ../../content/nw/src/nw_shell.cc:142
use 'child-clean-exit' on POSIX systems only
move kmNodejs switch to content
Remove the check of the name/id about the input element. Fix #434.
Merge pull request #445 from zhchbin/master

Remove the check of the name/id about the input element.
fix NOTREACHED case to launch devtools with debug version
Adding support for alternate icon in Mac
Added self to AUTHORS
fix traling whitespace and empty impl on Linux/Win

Fix previous commit
bump version to 0.4.2
[test]add option 'no_connect' in /nw_app_test
[test] add test case for #408
[README] update for 0.4.2
bump version to 0.4.3-pre
Merge pull request #454 from owenc4a4/test

[test] add test case for #408
Overriding method should have "virtual"

Fix warnings on OSX
add `nwsnapshot` to package tool
[test] test case for screen shot
Merge pull request #463 from owenc4a4/tool

add `nwsnapshot` to package tool
Merge pull request #464 from owenc4a4/test

[test] test case for screen shot