Remove references to deprecated platforms

There are no more "dm", "dam" and "cmf" platforms
=> MP will have to depend on other MP (<dependencies><package>nuxeo-dm:5.5</package></dependencies>, nuxeo-content-browser:1.0.0, nuxeo-content-browser:1.0.0-cmf, ...) instead of on the platform (<platforms><platform>cap-5.5</platform></platforms>, dm-5.5, ...)
=> The only existing platforms will be "cap" and "coreserver"