Provide Windows Linux Subsystem Bash Support

[dkocher]

BASH can be found in {{%SystemDrive%\Windows\System32\bash.exe}} Invoking commands in bash is done via command line parameter -c. This could be useful for any replacement of PuTTy. Things to check before falling back to PuTTy if BASH not found or SSH not installed on WSL:

• check bash.exe existence.
• try invoking ssh on bash.exe (monitoring Error Output)
• if failed: Invoke PuTTy fallback.

Would be a nice nice-to-have.

[dkocher]

In r46713.