Adding possibility for client to upload the file

This CL adds three features that will allow the client to upload the report
file.
Three main modifications are made :
- Allow upload url to have a file:// scheme, and write the HTTP request to file
  in that case
- Split the request in two parts in case of a file:// scheme, the request
  time and the response time. A new API [handleNetworkResponse] is added.
- Give the opportunity to the client to get the configuration NSDictionary
  to be able to recreate the breakpad context at response time.

Patch by Olivier Robin <olivierrobin@chromium.org>

Review URL: https://breakpad.appspot.com/2764002/

git-svn-id: http://google-breakpad.googlecode.com/svn/trunk@1368 4c0a9323-5329-0410-9bdc-e9ce6186880e