Add error type to validationError object
Closes #165
Fix with/without test when undefined
check if there are errors to return after stripping unknown properties
closes #167
Closes #168
Closes #163
Merge pull request #171 from HughePaul/bug-170

check if there are errors to return after stripping unknown properties - for issue #170
2.4.3
Merge branch 'feat-error-type' of git://github.com/ulrik59/joi into ulrik59
Closes #159
2.5.0