[SECURITY] Fedora 21 Update: libssh-0.6.4-1.fc21

The ssh library was designed to be used by programmers needing a working SSH implementation by the mean of a library. The complete control of the client is made by the programmer. With libssh, you can remotely execute programs, tra nsfer files, use a secure and transparent tunnel for your remote programs. With i ts Secure FTP implementation, you can play with remote files easily, without third-party programs others than libcrypto (from openssl).