Update Essentials/src/messages_pl.properties

Update Polish translations.
---
Date: 23.02.13
---
* Fixed "fireworkSyntax" (502)
* Fixed colors.
Merge pull request #356 from skmedix/patch-19

Update Essentials/src/messages_pl.properties
Merge pull request #352 from GunfighterJ/patch-15

[Fix] Persist yaw and pitch on teleport
Clarify vanish status a little.
[Feature] Allow IP lookup in /seen command.
[Permission] essentials.seen.ipsearch - allows /seen <ip address>
[Protect] Prevent creepers from breaking paintings if their explosions are disabled.
Backport from 3.0