add option for setting the wait_timeout in the AR adapter (this can be done in database.yml)

lib/active_record/connection_adapters/mysql2_adapter.rb

@@ -617,8 +617,13 @@ module ActiveRecord
           # Turn this off. http://dev.rubyonrails.org/ticket/6778
           variable_assignments = ['SQL_AUTO_IS_NULL=0']
           encoding = @config[:encoding]
+
+          # make sure we set the encoding
           variable_assignments << "NAMES '#{encoding}'" if encoding
 
+          # increase timeout so mysql server doesn't disconnect us
+          variable_assignments << "@@wait_timeout = #{@config[:wait_timeout] || 2592000}"
+
           execute("SET #{variable_assignments.join(', ')}", :skip_logging)
         end