Support Ruby 1.8 and 1.9 by rescuing Math::DomainError only if it is defined
Yahoo sometimes returns [nil] result, even if no error is listed

{"ResultSet"=>{"Quality"=>0, "Results"=>[nil], "Locale"=>"US", "Found"=>1, "version"=>"1.0", "ErrorMessage"=>"No error", "Error"=>0}}
Merge pull request #70 from benstein/patch-1

Yahoo sometimes returns [nil] result, even if no error is listed
Merge pull request #69 from ssorallen/master

Support Ruby 1.8 and 1.9 in mappable.rb
Merge remote-tracking branch 'upstream/master'
BUGFIX I sometimes get strings here

because of my json lib or yahoo?