* Capture Rack's "too many multipart files" error with a spec * Create a custom error class to handle Rack's multipart error * fixup! Capture Rack's "too many multipart files" error with a spec * Use our custom error class when Rack raises a multipart limit error * Use a Payload Too Large status code for TooManyMultipartFiles errors * Restore Rack's multipart limit after testing the failure * Upadate CHANGELOG * Reword CHANGELOG entry for MultipartPartLimitError change * Backticks around classname in CHANGELOG * Change next version of Grape from 1.6.3 to 1.7.0 The introduction of the TooManyMultipartFiles changes API behavior, so bump the minor version. * Include the system's configured multipart file limit in the error message The number of allowed multipart files is a configurable value in Rack, pull that limit and include it in the generated error message. * Add a note to UPGRADING about the new TooManyMultipartFiles exception