Add patch to fix Rails' hash types with Ruby 2.1.1

Might also help us with Ruby 2.2 until we have Rails 4.
Merge pull request #1244 from opf/fix/ruby_2.1.1_hash_select_and_reject

Add patch to fix Rails' hash types with Ruby 2.1.1
enabled ActiveRecord based session store and make it configurable
default to cache store in production
remove unnecessary calls to presence
make session store configurable via env var SESSION_STORE
set default in configuration.rb