The various `install` args should always be passed to salt-bootstrap.

Even when preforming config only, the install flags (i.e. -M, -S, -N),
are used by the bootstrap to determine which configs to copy.

This should help with #3542 and should supersede #3548.

plugins/provisioners/salt/provisioner.rb

@@ -106,7 +106,7 @@ module VagrantPlugins
 
         if configure && !install
           options = "%s -C" % options
-        else
+
         if @config.install_master
           options = "%s -M" % options
         end
@@ -126,7 +126,6 @@ module VagrantPlugins
         if @config.install_args
           options = "%s %s" % [options, @config.install_args]
         end
-        end
 
         if @config.verbose
           @machine.env.ui.info "Using Bootstrap Options: %s" % options