Refactor mapper types and leaf value handlers

[ljacqu]

• 107 Integrate ch.jalu.typeresolver

• 312 Support conversions from String in all property types

• Structure property types in classes more systematically
• Split leaf value handlers into a leaf value handler and mapper leaf types
• Refactor mapper leaf types to be more consistent with property types

[coveralls]

coverage: 99.39% (+0.07%) from 99.322% when pulling c96988f3dce344e3adc4f2b9bf805fa15da4eca4 on 312-property-type-refactor into b3008bdc1cb8bea9017a48f60a3b9e14afdf2be4 on configme-2-dev.