Update autocomplete.js

fix for problem, when setting 'minimum_characters': 0 doesn't work as it should (However, you may want the autocomplete to behave like a select. If you want that a simple click shows the autocomplete, set this to 0.)

initial query data should be empty, cuz there are nothing to compare in hasChanged
Merge pull request #170 from vosi/patch-1

Fixed uninitialized key.