Update server to 1.7.10

This commit upgrades the server to 1.7.10. This also means that the EULA must be accepted for the server to start up. This can be done manually by editing the `eula.txt` (ew, manually!), or by setting the `node['minecraft']['accept_eula']` attribute to true. We can't automatically accept EULAs for users, so this is false by default.

* Add attribute for accepting the EULA
* Write out a eula.txt resource with the content based on whether the EULA was accepted
* Some minor readme cleanup
Redundant use of `Object#to_s` in interpolation.<br>Prefer double-quoted strings unless you need single quotes to avoid extra backslashes for escaping.