Merge pull request #301 from lacostej/grant_admin

u3d/internals: grant_admin wasn't using has_admin_privileges? to get the privileges on non windows platforms

Author: lacostej

lib/u3d_core/command_executor.rb

@@ -144,6 +144,7 @@ def grant_admin_privileges(command)
         if Helper.windows?
           raise CredentialsError, "The command \'#{command}\' must be run in administrative shell" unless has_admin_privileges?
         else
+          raise CredentialsError, "The command \'#{command}\' must be run with admin privileges" unless has_admin_privileges?
           command = "sudo -k && echo #{cred.password.shellescape} | sudo -S bash -c \"#{command}\""
         end
         UI.verbose 'Admin privileges granted for command execution'