Upgrading version to 3.2.1-dev
Added possibility to use xhr object with credentials:
When there's a need to pass information about credentials in headers (e.g. cookie), "withCredentials" needs to be set to "true" on the xhr object.
Merge pull request #157 from vlamic/develop

Added possibility to use xhr object with credentials:
Added tests for withCredentials.
Added a cancelUpload function and tests for it.

The removeFile() function now cancels uploads if still active.

#55
Improved disable() and added tests for it.
Improved the disable and destroy methods and the tests.
Added download files.
Allow custom HTTP headers on file upload
Merge pull request #163 from chuggins/customize-request-headers

Allow custom HTTP headers on file upload
Cleaned up code a bit.
Encoding the X-File-Name header with encodeURIComponent now.

Closes #166
Added download files.
Upgrading version to 3.3.0 (Added .headers option and encoding X-File-Name now.)
Merge tag 'v3.3.0'

Added .headers option and encoding X-File-Name now.