Log Message:
Update ruby-multipart-post to 2.0.0.

=== 2.0.0 / 2013-12-21

- Drop Ruby 1.8 compatibility
- GH #21: Fix FilePart length calculation for Ruby 1.9 when filename contains
  multibyte characters (hexfet)
- GH #20: Ensure upload responds to both #content_type and #original_filename
  (Steven Davidovitz)
- GH #31: Support setting headers on any part of the request (Socrates Vicente)
- GH #30: Support array values for params (Gustav Ernberg)
- GH #32: Fix respond_to? signature (Leo Cassarani)
- GH #33: Update README to markdown (Jagtesh Chadha)
- GH #35: Improved handling of array-type parameters (Steffen Grunwald)