fixed up plugin system to work with v0.6

git-svn-id: http://svn.code.sf.net/p/retroshare/code/trunk@7287 b45a01b8-16f6-495d-af2f-9b41ad6348cc
fixed VOIP plugin to work with v0.6

git-svn-id: http://svn.code.sf.net/p/retroshare/code/trunk@7288 b45a01b8-16f6-495d-af2f-9b41ad6348cc