Fixing documentation formatting and copyright date (#32)

* Fixing text formatting and copyright date

Major update, mainly better version checks. (#30)

Note: API change to use the proper units as documented by Nagios. You may notice large jumps in your graphs if units were previously being ignored.
Note: Memory usage no-longer includes cache to match the way ‘docker stats’ does it. You likely will see a drop in memory usage from this.
Made version check much better, it can now handle non-official registries.
Added ability to specify size of a KB (1000 or 1024 bytes)
Moved testing to use Pytest
Added traceback to error handling for better bug reports.
Handle unsupported memory units better, i.e. not with assert.
Adjusted default registry to match Docker documentation.
Round and truncate displayed values as appropriate

Check swarm (#23)

Add swarm and service commands
Updated documentation
Added check_swarm to various test configurations