[API][WIN] Add show in taskbar API, both method and Window Subfields. Part #251
[API][WIN] Fix the SetShowInTaskbar didn't work well on Windows XP. Part #251
[API][GTK] Implement SetShowInTaskbar in GTK. Part #251
Implement SetShowInTaskbar on mac
Merge branch 'master' of https://github.com/richardcypher/node-webkit into skiptb
Merge pull request #1076 from richardcypher/skiptb

[MAC]implement on mac: hide the window from task bar while keeping it shown