Small defect fixed for when the base class is from an external library and a model has inheritance

Example, execution from a build phase script 

    mogenerator \
        -m "${modelPath}.xcdatamodeld/${modelVersion}" \
        --template-var arc=true \
        --includeh ${outDir}/${modelName}Model.h \
        --base-class GVCManagedObject \
        --base-class-import "<GVCCoreData/GVCCoreData.h>" \
        --machine-dir $outMachineDir \
        --human-dir $outDir

The model includes hierarchy like

    Type
    +--- SimpleType
    +--- ComplexType

Type inherits from GVCManagedObject, which is in the GVCCoreData framework (static lib), but SimpleType and ComplexType need to import Type.h   This patch fixes the issue where the subclasses did not import the super entity when it is local to the project.