Fix the month detection for lowercase and long abbreviated month names.

Let's try the usual case:

    >> I18n.locale = :en
    :en
    
    >> "18 October 2013".to_date
    Fri, 18 Oct 2013
    
    >> "18 october 2013".to_date
    Fri, 18 Oct 2013
    
    >> "18 oct 2013".to_date
    Fri, 18 Oct 2013
    
    >> "18 Oct 2013".to_date
    Fri, 18 Oct 2013

So far everything is ok. But in fact there are a lot of locales, which have lowercase and long abbreviated month names, like 'octobre' and 'oct.' in French.
    
    >> I18n.locale = :fr
    :fr
    
    >> "18 Octobre 2013".to_date
    ArgumentError: invalid date
      from /home/exoth/.rvm/gems/ruby-1.9.3-p448@jetradar/bundler/gems/timeliness-9c8161f4ab08/lib/timeliness/core_ext/string.rb:12:in `new'
      from /home/exoth/.rvm/gems/ruby-1.9.3-p448@jetradar/bundler/gems/timeliness-9c8161f4ab08/lib/timeliness/core_ext/string.rb:12:in `to_date'
      from (irb):39
      from /home/exoth/.rvm/gems/ruby-1.9.3-p448@jetradar/gems/railties-3.2.14/lib/rails/commands/console.rb:47:in `start'
      from /home/exoth/.rvm/gems/ruby-1.9.3-p448@jetradar/gems/railties-3.2.14/lib/rails/commands/console.rb:8:in `start'
      from /home/exoth/.rvm/gems/ruby-1.9.3-p448@jetradar/gems/railties-3.2.14/lib/rails/commands.rb:41:in `<top (required)>'
      from /home/exoth/projects/jetradar/script/rails:6:in `require'
      from /home/exoth/projects/jetradar/script/rails:6:in `<top (required)>'
      from -e:1:in `load'
      from -e:1:in `<main>'
    
    >> "18 octobre 2013".to_date
    ArgumentError: invalid date
      from /home/exoth/.rvm/gems/ruby-1.9.3-p448@jetradar/bundler/gems/timeliness-9c8161f4ab08/lib/timeliness/core_ext/string.rb:12:in `new'
      from /home/exoth/.rvm/gems/ruby-1.9.3-p448@jetradar/bundler/gems/timeliness-9c8161f4ab08/lib/timeliness/core_ext/string.rb:12:in `to_date'
      from (irb):41
      from /home/exoth/.rvm/gems/ruby-1.9.3-p448@jetradar/gems/railties-3.2.14/lib/rails/commands/console.rb:47:in `start'
      from /home/exoth/.rvm/gems/ruby-1.9.3-p448@jetradar/gems/railties-3.2.14/lib/rails/commands/console.rb:8:in `start'
      from /home/exoth/.rvm/gems/ruby-1.9.3-p448@jetradar/gems/railties-3.2.14/lib/rails/commands.rb:41:in `<top (required)>'
      from /home/exoth/projects/jetradar/script/rails:6:in `require'
      from /home/exoth/projects/jetradar/script/rails:6:in `<top (required)>'
      from -e:1:in `load'
      from -e:1:in `<main>'
    
    >> "18 oct. 2013".to_date
    NoMethodError: undefined method `map' for nil:NilClass
      from /home/exoth/.rvm/gems/ruby-1.9.3-p448@jetradar/bundler/gems/timeliness-9c8161f4ab08/lib/timeliness/core_ext/string.rb:11:in `to_date'
      from (irb):43
      from /home/exoth/.rvm/gems/ruby-1.9.3-p448@jetradar/gems/railties-3.2.14/lib/rails/commands/console.rb:47:in `start'
      from /home/exoth/.rvm/gems/ruby-1.9.3-p448@jetradar/gems/railties-3.2.14/lib/rails/commands/console.rb:8:in `start'
      from /home/exoth/.rvm/gems/ruby-1.9.3-p448@jetradar/gems/railties-3.2.14/lib/rails/commands.rb:41:in `<top (required)>'
      from /home/exoth/projects/jetradar/script/rails:6:in `require'
      from /home/exoth/projects/jetradar/script/rails:6:in `<top (required)>'
      from -e:1:in `load'
      from -e:1:in `<main>'
    
    >> "18 Oct. 2013".to_date
    NoMethodError: undefined method `map' for nil:NilClass
      from /home/exoth/.rvm/gems/ruby-1.9.3-p448@jetradar/bundler/gems/timeliness-9c8161f4ab08/lib/timeliness/core_ext/string.rb:11:in `to_date'
      from (irb):45
      from /home/exoth/.rvm/gems/ruby-1.9.3-p448@jetradar/gems/railties-3.2.14/lib/rails/commands/console.rb:47:in `start'
      from /home/exoth/.rvm/gems/ruby-1.9.3-p448@jetradar/gems/railties-3.2.14/lib/rails/commands/console.rb:8:in `start'
      from /home/exoth/.rvm/gems/ruby-1.9.3-p448@jetradar/gems/railties-3.2.14/lib/rails/commands.rb:41:in `<top (required)>'
      from /home/exoth/projects/jetradar/script/rails:6:in `require'
      from /home/exoth/projects/jetradar/script/rails:6:in `<top (required)>'
      from -e:1:in `load'
      from -e:1:in `<main>'

So that pull request fixes the month detection behavior to properly handle such situations.