Implement remaining libssh2 API by pkittenis · Pull Request #1 · ParallelSSH/ssh2-python

…ended data methods.

Implemented session get/set blocking, get/set timeout and scp methods and integration tests.
Updated agent connection error exception.
 Updated session method name to match libssh2.
Implemented file info extension class for SCP file stat structure.

Conditionally include new libssh2 API endpoints, default to false for compatibility with older versions of libssh2.