Merge pull request #2 from lslezak/workshop_adaptation_for_conversion

Added substring() built-in
use correct test name
add to_s method for path, so it produce nicer output
add missing require
implement first two ops in runtime
add comparison operation
swig is not used, so don't require it
allow separate usage of logger
quite big change to finish operations, that leads to changes in various type. Ops is now finished.
more ycp demonstration for ops implementation
adapt ruby to ycp conversion for path
implement builtin ops add
change parameter name to be consistent
implement builtin ops subtract
implement builtins ops multiply, divide, modulo
implement builtin bitwise ops
implement builtin shift ops
implement builtin logical ops
implement builtin unary ops
add forgotten YCP namespace