spring-cloud-netflix: Any multipart request with a boundary in the content type raises an exception

In 1.3.0.M1 seems that a bug has been introduced.

Any multipart request that in his Content-Type adds the boundary parameter (in theory a required parameter, see RFC) raises an exception with the message “MIME type may not contain reserved characters”.

I think it has been introduced in the commit which tries to handle well a content-type with a charset due to the upgrade of the httpclient library.

I will try to open a PR with a fix in order to have it for this release.