[MERGE] Support for Putty SSH implementation

[Dmitry Vasiliev]

Alexander Belchenko wrote:
> Dmitry Vasiliev пишет:
>> The attached patch adds support for Putty's plink SSH implementation.
>> Also slightly refactored SSH negotiation code and added some tests.
> 
> What's improvements of using plink instead of paramiko?

I think the main advantage is easy adoption for novices. Someone can try bzr 
without even installing anything.

-- 
Dmitry Vasiliev (dima at hlabs.spb.ru)
     http://hlabs.spb.ru