implemented more tests and fixed a few bugs in GxsSecurity

git-svn-id: http://svn.code.sf.net/p/retroshare/code/trunk@7683 b45a01b8-16f6-495d-af2f-9b41ad6348cc
fixed bug caused by old GXS keys in distant chat. Added a security warning for these keys to be deleted.

git-svn-id: http://svn.code.sf.net/p/retroshare/code/trunk@7684 b45a01b8-16f6-495d-af2f-9b41ad6348cc