Remove cache, add disable-offline-access config node

Fixes various permissions not being respected during login/logout with inventories already open. This will result in a performance hit for repeated open/closes - there will be significantly more disk I/O.

Closes lishid#171
Closes #56

plugin/src/main/resources/config.yml

@@ -1,4 +1,5 @@
-config-version: 4
+config-version: 5
 settings:
+  disable-offline-access: false
   disable-saving: false
   locale: 'en_us'