Remove Get-NServiceBusVersion, fixes #2, related to https://github.com/Particular/NServiceBus/issues/1852

Update the lnstall-NServiceBusLicense to put licenses in the HKLM\ParticularSoftware\NServiceBus, fixes #3, related to https://github.com/Particular/NServiceBus/issues/1852
rename cmdlet to Get-NServiceBusLicense
Merge remote-tracking branch 'upstream/develop' into get-license_cmdlet
updated to address comments in https://github.com/Particular/NServiceBus.PowerShell/pull/4

- updated registrykey used to read license
- expirydate is now output as a date since it seems the most important attribute of a license