Small refactoring
Refactoring: Extracted code from AddSingleItemActionHandler. Issue #46
Fixed test RebuildThumbnailActionHandlerTest
Fixed text
Fixed bug in imports
Renamed a function
Extracted code from AddManyItemsActionHandler. Issue #46
Extracted code from AddManyItemsRecursivelyActionHandler
Removed base class AddManyItemsAbstractActionHandler
Improved addManyItemsRecursively. Some code clean up.
Changed behaviour of add many items recursively...

Now when user adds to repository directory tmp, then in the
repo a tmp directory will be created. Later in the repo was created only
the contents of tmp directory, but not itself.
Refactoring: renamed a field
Comments
Fixed bug
Almost done with AddItemsActionHandler. Issue #46
Working on FileDialog class