Handle various access code errors

[hone]

when a feature isn't estimated and trying to start it:

hone@hone-x200:~/Projects/oib/git_pivot$ git_pivot start --id 1037065
/opt/ruby-enterprise-1.8.6-20090201/lib/ruby/gems/1.8/gems/rest-client-1.0.3/lib/restclient/request.rb:195:in process_result': HTTP status code 422 (RestClient::RequestFailed) from /opt/ruby-enterprise-1.8.6-20090201/lib/ruby/gems/1.8/gems/rest-client-1.0.3/lib/restclient/request.rb:125:intransmit'
from /opt/ruby-enterprise-1.8.6-20090201/lib/ruby/1.8/net/http.rb:543:in start' from /opt/ruby-enterprise-1.8.6-20090201/lib/ruby/gems/1.8/gems/rest-client-1.0.3/lib/restclient/request.rb:123:intransmit'
from /opt/ruby-enterprise-1.8.6-20090201/lib/ruby/gems/1.8/gems/rest-client-1.0.3/lib/restclient/request.rb:49:in execute_inner' from /opt/ruby-enterprise-1.8.6-20090201/lib/ruby/gems/1.8/gems/rest-client-1.0.3/lib/restclient/request.rb:39:inexecute'
from /opt/ruby-enterprise-1.8.6-20090201/lib/ruby/gems/1.8/gems/rest-client-1.0.3/lib/restclient/request.rb:17:in execute' from /opt/ruby-enterprise-1.8.6-20090201/lib/ruby/gems/1.8/gems/rest-client-1.0.3/lib/restclient/resource.rb:66:input'
from /opt/ruby-enterprise-1.8.6-20090201/lib/ruby/gems/1.8/gems/hone-pivotal-tracker-0.0.4/lib/pivotal-tracker.rb:67:in update_story' from /home/hone/Projects/oib/git_pivot/lib/git_pivot.rb:67:instart_story'
from /home/hone/Projects/oib/git_pivot/lib/runner.rb:51:in send' from /home/hone/Projects/oib/git_pivot/lib/runner.rb:51:inrun'
from /home/hone/Projects/oib/git_pivot/bin/git_pivot:8