ActiveResource::Connection should rescue from Timeout::Error

Net::HTTP can raise a Timeout::Error for both legitimate reasons (slow/unresponsive server) and the problems described in http://headius.blogspot.com/2008.... Right now, ARes emits this unhelpful exception+trace since there's no rescue block:

 execution expired
 /usr/lib/ruby/1.8/timeout.rb:54:in `rbuf_fill'
 /usr/lib/ruby/1.8/timeout.rb:54:in `rbuf_fill'
 /usr/lib/ruby/1.8/timeout.rb:56:in `timeout'
 /usr/lib/ruby/1.8/timeout.rb:76:in `timeout'
 /usr/lib/ruby/1.8/net/protocol.rb:132:in `rbuf_fill'
 /usr/lib/ruby/1.8/net/protocol.rb:116:in `readuntil'
 /usr/lib/ruby/1.8/net/protocol.rb:126:in `readline'
 /usr/lib/ruby/1.8/net/http.rb:2017:in `read_status_line'
 /usr/lib/ruby/1.8/net/http.rb:2006:in `read_new'
 /usr/lib/ruby/1.8/net/http.rb:1047:in `request'
 /usr/lib/ruby/1.8/net/http.rb:1034:in `request'
 /usr/lib/ruby/1.8/net/http.rb:543:in `start'
 /usr/lib/ruby/1.8/net/http.rb:1032:in `request'
 /usr/lib/ruby/1.8/net/http.rb:769:in `get'
 [RAILS_ROOT]/vendor/rails/activeresource/lib/active_resource/connection.rb:110:in `send'
 [RAILS_ROOT]/vendor/rails/activeresource/lib/active_resource/connection.rb:110:in `request'

 ... SNIP

This patch rescues from Timeout::Error explicitly, introduces an ActiveResource::TimeoutError that is a child of ActiveResource::ConnectionError.