Split conf classes

In order to write unit tests, we often need several configuration files loaded at the same time. Until now all configuration files got assigned to Dcmgr.conf regardless of whether we were talking about hva.conf, dcmgr.conf, sta.conf etc.

The new usage is:
      Dcmgr::Configurations.hva # => accesses hva.conf
      Dcmgr::Configurations.dcmgr # => accesses dcmgr.conf
      Dcmgr::Configurations.sta # => accesses sta.conf
      etc.

This also makes the code easier to read since it shows which config file is being accesses.

The old Dcmgr.conf method currently still works but is considered deprecated and will print a big ugly message in the logs whenever used. Please update it to the new format if you encounter it. I've already done this for a large portion of the code.