[MERGE] Support for Putty SSH implementation

[Alexander Belchenko]

Alexander Belchenko has voted -0.
Status is now: Semi-approved
Comment:
It's looks good, but it does not work on my Windows XP:

C:\work\Bazaar\sandbox\bzr.dev>plink -V
plink: Release 0.58

C:\work\Bazaar\sandbox\bzr.dev>bzr push 
sftp://bialix@aaronbentley.com/~/repo/bzr.dev/
Unable to open connection:
Host does not existbzr: ERROR: Unable to connect to SSH host 
aaronbentley.com; EOF during negotiation

For details, see: 
http://bundlebuggy.aaronbentley.com/request/%3C459FE39B.2080608%40hlabs.spb.ru%3E