Tiles blocking boss levels display variable instead of localized text

[Bumber64]

Describe the bug
The tiles blocking the staircase to the air wizard and the obsidian dungeon display variable names instead of localized text. E.g., minicraft.notification.gem_pickaxe_required

To Reproduce

1. Try to mine air wizard entrance with a wooden pickaxe.
2. Try to mine obsidian dungeon entrance wall without defeating the air wizard.

Expected behavior
Should be localized text, e.g., Gem pickaxe required.

Desktop

• OS: Windows 8.1
• Game version: 2.3.0-dev2