Optimized Network Lib: Sleep, Extended Timeouts

- Update of Network Lib to coincide with core RF24 lib optimization
- added extended timeouts:
- in write_to_pipe - changed from radio read with retries, to writefast
with standby(timeout)
- removed retries from network write, as retries will be handled by the
timeout period
- added transmitTimeout variable
- added built-in sleep functionality
- updated example files and documentation