remove duplicated include line from polygon_array_display.h

this duplication and quates in #include line happens compilation error about
moc file of qt4
depends on rviz using <depend> tag, because rviz failed to detect plugins from jsk_rviz_plugins without depend tag
Merge pull request #10 from garaemon/fix-failed-to-load-plugin

Fix failed to load plugin of jsk_rviz_plugins