Fixed bug in staff filter on all positions admin screen, which was conflicting with other admin screen filters. Re-wrote that staff (taxonomy) filter and put a fix in pre_get_posts fliter in mstw_coaching_staffs.

git-svn-id: https://plugins.svn.wordpress.org/coaching-staffs/trunk@1039239 b8457f37-d9ea-0310-8a92-e5e31aec5664