Merge pull request #41 from pentie/ptuse

Thanks for contribute from @pentie
Merge pull request #42 from pentie/master

Add support for update_with_media request
Escape leading '@' when POSTing as multipart/form-data

Would cause cURL to treat the field as a filename.
Merge pull request #49 from jimmyxu/parameters

Escape leading '@' when POSTing as multipart/form-data