Added SHA512 for entry
Merge pull request #16 from matthiasbeyer/add-entry_hash

Added SHA512 for entry
Removed all old stuff from README
Implemented CatCommand class
The cat command is an ExecuteableCommand
Added raw output option when "cat"ing
Outsourced actual catting into protected helper method
Added module for special commands which want to execute but also to query
Added CatLastCommand implementation (partly)
Added module for commands which need to read the config
Refactored CatLastCommand class