v1.5.1

This patch release fixes some issues that inadvertently made it into v1.5:

• Document newly added /modjail command (#37)
• The plugin would fail to load on certain old versions (e23de7d)
• Fix /jail command not working for online players first joining the server (#38)

Full Changelog: v1.5...v1.5.1

Thanks to @rymiel for helping with this release.