Update Unicode Version to 9.0.0

9.0.0 was released on June 21, 2016

http://blog.unicode.org/2016/06/announcing-unicode-standard-version-90.html

http://www.unicode.org/versions/Unicode9.0.0/

There are some changes about grapheme cluster in Unicode 9.0.0:

http://unicode.org/reports/tr29/#Grapheme_Cluster_Boundary_Rules

------------

I noticed that `unpack_graphemes` returns [Other] when the argument is Other ÷ Prepend
(it must be [Other, Prepend]).
But in [Unicode 8.0.0's Prepend has no characters](http://www.unicode.org/reports/tr29/tr29-27.html#Prepend)
so we don't have to backport following patch:

```diff
should_break =
+ if pos == eoc
+   true
```

1 files changed, 3 insertions, 1 deletions

diff --git a/activesupport/bin/generate_tables b/activesupport/bin/generate_tables
index 5d912f375c..aa36a01b5b 100755
--- a/activesupport/bin/generate_tables
+++ b/activesupport/bin/generate_tables
@@ -8,6 +8,7 @@ end
 
 require "open-uri"
 require "tmpdir"
+require "fileutils"
 
 module ActiveSupport
   module Multibyte
@@ -101,9 +102,10 @@ module ActiveSupport
 
         def parse
           SOURCES.each do |type, url|
-            filename = File.join(Dir.tmpdir, "#{url.split('/').last}")
+            filename = File.join(Dir.tmpdir, UNICODE_VERSION, "#{url.split('/').last}")
             unless File.exist?(filename)
               $stderr.puts "Downloading #{url.split('/').last}"
+              FileUtils.mkdir_p(File.dirname(filename))
               File.open(filename, "wb") do |target|
                 open(url) do |source|
                   source.each_line { |line| target.write line }