(maint) Update file mode for future parser

The future parser preserves number literals as actual numbers. This
causes problems for modes on file resources because 640 is the decimal
number 640 and not the octal 640.
(maint) Stop leaking file handles

File.new(f) results in a file handle being used. The test manifest in
this case ended up leaking file handles which caused the master to run
out of file handles while serving a request. This lead to a consistent
failure on the first thread requesting the catalog where the error
reported was:

  Could not autoload puppet/type/notify: no such file to load -- /usr/lib/ruby/site_ruby/1.8/puppet/type/notify.rb

The error was misleading. The underlying problem was not an ENOENT, but
an EMFILE (Too many open files). By switching to File.read(f) the
manifest will no longer leak file handles.