Merge pull request #376 from adrianschroeter/master

- fail when a product plugin dir is configured, but does not exist
- Fixed --help output for disk-alignment
  The option value must be given in KBytes but the help did
  not explain that and the default value information used the
  wrong unit too
Merge pull request #377 from adrianschroeter/master

- Avoid unexpected warnings in product media code
- Support LUKS extension with LVM
- Add info messages for intermediate steps when creating the
  disk layout such like information about creation of md raid
  or luks extensions
- Call cryptsetup in one central encoding function in
  KIWIBoot for disk based images
- Added check for given type name on the commandline compared to
  the selected build type in the checkType global function.
  If the commandline specified type is valid but not specified
  in the configuration kiwi exits
- Don't call losetup with stderr redirected to stdout if the
  show option is used. potential error messages could then
  affect the standard output
- Make sure LUKS encoding is not applied if the given device
  already contains a LUKS container
- Fixed OEM installer for LVM on LUKS images
- Avoid blocking IO in callCmd if large chunks of data arrive
- use count information from IO::Select to loop through
  available data for reading
- Fixed logging module
  * delete obsolete and unused code from KIWILog
  * make sure error log messages are printed on stderr
  * delete obsolete --log-port option
- Delete git from Recommends list in the spec file
  SUSE by default installs all recommended packages which
  increases the amount of software installed when kiwi is
  installed by an unnecessary number of packages
- Update bash completion
  Added possible options for --upgrade
- Fixed typo in message texts
- DB: rebuild documentation
- Improve logging of errors for session scripts
  kiwi creates session scripts running in screen logging all
  output to the kiwi logfile. In case of an error we only want
  to see the stderr information and not the entire history
Merge pull request #379 from openSUSE/review_140728_callcmd_no_block

- Implement non blocking I/O for reading results from commands called in the distribution plugins
- Be more clear in variable assignment with regards to name vs. content