Move functions from slivka.utils.__init__ to appropriate modules.

[warownia1]

Tidy up utils package moving all of the __init__ content to other modules.

• [ ] Move Singleton, _cachedproperty, _ttlcache, _classproperty, _aliasproperty, deprecated and _getclasspath to utils.functools
• [ ] Move JobStatus to consts
• [ ] Move LimitedSizeDict, _flattenmapping and _unflattenmapping to utils.collections
• [ ] Move ConfigYamlLoader, includeconstructor, mappingconstructor to conf.loaders