Extracting the primaryKey reading code into a new function to prevent errors
Using an array primaryKey value in TreeBehaviorTests to confirm that it is not a problem
Not baking tables with array-valued primary key where there is only,
one key, as in most cases it is just a hassle for end users
Merge pull request #3960 from cakephp/3.0-treebehavior-fixes

3.0 treebehavior fixes