WIP refactor yaml generation and hostname extraction
move checks for undefined variables to the YamlConfig

Where it belongs!
encapsulate host_name as a property of YamlConfig
move YamlConfig to yaml_config module
remove close not needed in context manager
refactor OutputWriter
etag reading and comparison
remove spare empty line
test the constructor of the MonitoringConfigGenerator main class
start testing the generate method
nuke the InputReader
remove the dependency on httplib2
remove the import of the CONFIG, not needed anymore
implement a Header class to encapsulate the etag and mtime information
clean and fixup is_newer_than, finally
Merge pull request #4 from ImmobilienScout24/refactor/moar

Refactor/moar