Update linter-plus.coffee
Update linter-plus.coffee

Fix a copy/paste error in `deleteProjectMessages`.
steelbrain/linter,UltCombo/linter,mdgriffith/linter,shawninder/linter,iam4x/linter,e-jigsaw/Linter,AtomLinter/Linter,DanPurdy/linter,blakeembrey/linter,kaeluka/linter,AsaAyers/linter,JohnMurga/linter,atom-community/linter,levity/linter,elkeis/linter,Arcanemagus/linter