regex check that external ids are valid ids before wrapping in href
regex check that external ids are valid ids before wrapping in href

wilke/MG-RAST,MG-RAST/MG-RAST,teharrison/MG-RAST,MG-RAST/MG-RAST,MG-RAST/MG-RAST,wilke/MG-RAST,paczian/MG-RAST,paczian/MG-RAST,wilke/MG-RAST,teharrison/MG-RAST,teharrison/MG-RAST,paczian/MG-RAST,paczian/MG-RAST,teharrison/MG-RAST,MG-RAST/MG-RAST,teharrison/MG-RAST,wilke/MG-RAST,wilke/MG-RAST,MG-RAST/MG-RAST,teharrison/MG-RAST,wilke/MG-RAST,wilke/MG-RAST,paczian/MG-RAST,paczian/MG-RAST