This update is kind of large for several reasons, read below changelog for more details.
Also it occurs to me I probably should've released an update 1-2 months ago.
Also, due to difficulties there is currently no support to add parrots to player disguises.

• Updated to 1.12, added two new mobs (Illusioner and Parrot)
• Added backwards support for 1.11.2 (Premium Only)
• Plugin now can save GameProfiles locally instead of constantly fetching from Mojang's servers.
• Added ability to save disguises so they remain even after restarts, reloads, chunk unloads, etc. (Premium Only)
• Removed config option to keep disguises after entity deaths, chunk unloads, etc. Saved disguises now handles this.
• Fixed some issue that had something to do with scoreboards and UUIDs, below name title perhaps?
  
• Skins on player disguises don't break as often
  
• Added saner values for slime size and AreaEffectCloud size
• Fixed self disguise pushing
• Disguised creepers no longer play the warning sound
  
• Lots of code cleanups

If you purchased the plugin but want to use a development build, just stick the premium version of the plugin in your LibsDisguises folder.