Flush all log output and sleep a bit for NFS export warning [closes GH-119]

lib/vagrant/hosts/bsd.rb

@@ -23,7 +23,11 @@ module Vagrant
                                          :ip => ip,
                                          :folders => folders)
 
+        # The sleep ensures that the output is truly flushed before any `sudo`
+        # commands are issued.
         env.logger.info "Preparing to edit /etc/exports. Administrator priveleges will be required..."
+        sleep 0.5
+
         output.split("\n").each do |line|
           # This should only ask for administrative permission once, even
           # though its executed in multiple subshells.

lib/vagrant/hosts/linux.rb

@@ -25,6 +25,8 @@ module Vagrant
                                          :folders => folders)
 
         env.logger.info "Preparing to edit /etc/exports. Administrator priveleges will be required..."
+        sleep 0.5
+
         output.split("\n").each do |line|
           # This should only ask for administrative permission once, even
           # though its executed in multiple subshells.

lib/vagrant/util/plain_logger.rb

@@ -3,6 +3,17 @@ module Vagrant
     # Subclass of the standard library logger which has no format on
     # its own. The message sent to the logger is outputted as-is.
     class PlainLogger < ::Logger
+      # This is the method which is called for all debug, info, error,
+      # etc. methods by the logger. This is overriden to verify that
+      # the output is always flushed.
+      #
+      # Logger by default syncs all log devices but this just verifies
+      # it is truly flushed.
+      def add(*args)
+        super
+        @logdev.dev.flush if @logdev
+      end
+
       def format_message(level, time, progname, msg)
         # We do no formatting, its up to the user
         "#{msg}\n"