Stringify minidump stream_type constants in minidump_dump output
R=mark at https://breakpad.appspot.com/3704002/

git-svn-id: http://google-breakpad.googlecode.com/svn/trunk@1347 4c0a9323-5329-0410-9bdc-e9ce6186880e
Ensure C:/Dumps/ exists in crash_generation_app
A=j.turney
R=ted at https://breakpad.appspot.com/1134002/

git-svn-id: http://google-breakpad.googlecode.com/svn/trunk@1348 4c0a9323-5329-0410-9bdc-e9ce6186880e