* Fix getExtensionPageUrl on Windows
Signed-off-by: Lauri Nevala <lauri.nevala@gmail.com>

* Use path.posix.join() instead
Signed-off-by: Lauri Nevala <lauri.nevala@gmail.com>

* Fix lint issues
Signed-off-by: Lauri Nevala <lauri.nevala@gmail.com>