Add default connect and read timeouts for HttpUrlConnection.
Merge pull request #246 from square/jw/timeouts

Add default connect and read timeouts for HttpUrlConnection.
Add static method headers to header list when present.
Merge pull request #249 from square/jw/static-headers

Add static method headers to header list when present.
Allow 'null' parts to remove from request.

This is useful for specifying optional parts in a multipart request without requiring extra logic at the call site.
Merge pull request #251 from square/jw/optional-part

Allow 'null' parts to remove from request.
Prepare version 1.1.1.
[maven-release-plugin] prepare release parent-1.1.1
[maven-release-plugin] prepare for next development iteration
Spelling.
Special case String type for multi-part parts.
Merge pull request #252 from square/jw/strings

Special case String type for multi-part parts.