Revert "Chapter3 Example6: renamed request DTO to be in line with ServiceStack guidelines"

This reverts commit cd2c1aaff17a1ae82059545ff3d4d6c320a8cf47.
Revert "Chapter3 Example 6: bicycles PUT request and validation"

This reverts commit 615b03c7c04f2439f9f959aaf41c9f0b2cfb938b.