Bump ssh2 dependency version

Update to use most recent ssh2 release

Add exmaple of using exists()

Update documentation

Bug fix for issue #187

Bug in exist() method when testing the root directory caused an infinite loop.

Documentation and examples

Minor documentation and example fixes. Added new examples to example directory

Windows path fixes

Bugfix release addressing problems with paths on environments where the client and server are on different platforms, with one being windows and the other unix.

Improve error reporting for multiple ssh2-sftp-client clients

Added ability to set a client name.
Added work-around for SSH2 'end' event issue during connect
Add additional error checking to prevent calling connect on already connected client

Path enhancement version

Increased error checking and better handling of relative (i.e. ./path and ../path) paths

Documentation Fix

Clarify get() arguments.

Ensure get() return value is consistent.

Bugfix release for mkdir path bug

Minor fix to enable mkdir to handle relative paths correctly.

Minor package fixes

Remove additional files in package that are not required.

Version 4.0.0 release

Many bug fixes, new event handling and updated documentation