DOC: filter.d./pure-ftpd doco from wiki
DOC: filter.d/vsftpd doco from wiki
BF: add expression for ssh filter for code 3: SSH2_DISCONNECT_KEY_EXCHANGE_FAILED. closes gh-289
Merge pull request #559 from grooverdan/pure-ftpd-doco

DOC: filter.d/pure-ftpd doco from wiki
Merge pull request #560 from grooverdan/vsftpd-doco

Vsftpd doco
Merge pull request #563 from grooverdan/gh-289-ssh

BF: add expression for ssh filter for code 3: SSH2_DISCONNECT_KEY_EXCHAN...