A fix and some new placeholders

[aBooDyy]

Fixed the flags placeholder issue that was reported in #8.
Added new placeholder %worldguard_region_has_flag_FLAG% suggested in #6.
Added the placeholders from the old version

%worldguard_region_max_point_x% 
%worldguard_region_max_point_y% 
%worldguard_region_max_point_z% 
%worldguard_region_min_point_x% 
%worldguard_region_min_point_y% 
%worldguard_region_min_point_z% 

All placeholders seemed to work fine with latest WG (v7,0.1) in Spigot v1.4.4.