ESB 3.5.4: WebDAV proxying, bug fixes (News from 14.11.)

A series of improvements allows Membrane ESB to be used as proxy for a Subversion repository using WebDAV. Beyond that, 3.5.4 reduces memory usage, fixes a few issues and has a new LoginInterceptor, which will be the subject of a separate post in the future. Due to the move to Github, the changelog has a new location.