curl now can uploading file with ',' or ';' in filename.

original patch is at http://sourceforge.net/p/curl/bugs/1171/
here's the updated one, with docs, and test cases.

this commit will make curl support http form uploading file with ',' or ';' in its filename, by support parse double-quotes around the file and filename part.
Which does not change the behavior of curl of any existed external usage, just support parse file and filename which is well quoted, if the caller does quoting the file or the filename part..