Update ruby-net-ssh to 2.5.2.
=== 2.5.2 / 25 May 2012
* Fix for Net::SSH::KnownHosts::SUPPORTED_TYPE [Marco Sandrini]
=== 2.5.1 / 24 May 2012
* Added missing file to manifest [Marco Sandrini]
=== 2.5.0 / 24 May 2012
* Implement many algorithms [Ryosuke Yamazaki]
* Key Exchange
* diffie-hellman-group14-sha1
* ecdh-sha2-nistp{256,384,521}
* Host Key
* ecdsa-sha2-nistp{256,384,521}
* Authentication
* ecdsa-sha2-nistp{256,384,521}
* HMAC
* hmac-ripemd160
* Cipher:
* aes{128,192,256}-ctr
* camellia{128,192,256}-ctr
* blowfish-ctr
* cast128-ctr
* 3des-ctr
* arcfour (has problems with weak keys, and should be used with caution)
* camellia{128,192,256}-cbc
=== 2.4.0 / 17 May 2012
* Support for JRuby + Pageant + Windows [arturaz]
5bb6151de0