On a windows system having a file path like '/tmp/' . md5(microtime(true)) caused problems. I've updated this to use the system temp directory.
I've replaced the requirement for the pecl yaml extension with the symphony component. Sometimes I work on a windows box and the instructions for installing pecl yaml on windows looked a little intimidating:

https://code.google.com/p/php-yaml/wiki/InstallingWithPecl
Merge pull request #8 from meadsteve/master

Fix temp directory for ssh-keygen on windows systems