Fail CI with JS unit test coverage below 100%

This helps us into keeping the coverage.

spec/teaspoon_env.rb

@@ -181,6 +181,6 @@ Teaspoon.configure do |config|
     #coverage.statements = nil
     #coverage.functions = nil
     #coverage.branches = nil
-    #coverage.lines = nil
+    coverage.lines = 100 if ENV["CI"] == 'true'
   end
 end