Fixed indentation and excessive spaces
fixed bug with logout() method that caused sessions to remain open in the netscaler.
Fixed NSNitro.login() error reporting

Fixes #27
added much-needed nitro.logout() calls to each cmd in nsnitrocmd.py to avoid session leaks.
fixed indentation issues
Fix: Wrong serialization of the payload
Add support for IPv4 routes and PBR resources.
iptunnel implementation
Fix: get_sysname function definition
Add: NSIPTunnel
Merge branch 'master' of https://github.com/atopuzov/nsnitro