Hydrator doesn't work for boolean field types that start with "is"

My Doctrine entity has a isApproved method and a setIsApproved method. But my field is also called isApproved and not just approved. Only with the supplied code in this pull request that will work.
Added test
Added isActive to object manager mapping
Added new test instead of modifying existing test
#428 - minor cs fixes, using strict comparison for strings
Merge branch 'feature/#428-support-isser-method-on-is-fields'

Close #428