Do not use the syck YAML engine

We started using the syck engine in some cases to
solve a roblem that
a) we can't reproduce now
b) we can solve in another way

This is the other solution. To have special logic
for empty YAML files.

The reason why we want to avoid syck is that it
gets into encoding problems with the configuration
of Style/WordArray, which contains a regular
expression.
Merge pull request #1385 from jonas054/fix_yaml_crash

Do not use the syck YAML engine