Update PostgreSQL documentation (9.6.3, 9.5.7, 9.4.12)

Fixes #632.

lib/docs/filters/postgresql/clean_html.rb

@@ -52,7 +52,7 @@ module Docs
           node.content = node.content
         end
 
-        css('pre code', 'pre span').each do |node|
+        css('pre code', 'pre span', 'pre i', 'pre samp', 'code code', 'code span').each do |node|
           node.before(node.children).remove
         end
 

lib/docs/filters/postgresql/entries.rb

@@ -108,6 +108,7 @@ module Docs
           entries.concat get_custom_entries('.TABLE td:first-child > code')
         when 'functions-string'
           entries.concat get_custom_entries('> div[id^="FUNC"] td:first-child > code')
+          entries.concat get_custom_entries('> div[id^="FORMAT"] td:first-child > code')
         else
           if type && type.start_with?('Functions')
             entries.concat get_custom_entries('> .TABLE td:first-child > code.LITERAL:first-child')

lib/docs/scrapers/postgresql.rb

@@ -56,17 +56,17 @@ module Docs
     HTML
 
     version '9.6' do
-      self.release = '9.6.2'
+      self.release = '9.6.3'
       self.base_url = 'https://www.postgresql.org/docs/9.6/static/'
     end
 
     version '9.5' do
-      self.release = '9.5.6'
+      self.release = '9.5.7'
       self.base_url = 'https://www.postgresql.org/docs/9.5/static/'
     end
 
     version '9.4' do
-      self.release = '9.4.11'
+      self.release = '9.4.12'
       self.base_url = 'https://www.postgresql.org/docs/9.4/static/'
     end
   end