defined a test to save and load a column
saving columns
loader and saver moved to a package called filesystem
column id is created internally, so it is possible to define two columns with the same name
defining new tests for save and load tasks
to avoid duplicate code, loader and saver merged with the BoardManager
the mock models are storing the UUID as string to avoid constantly doing cast
tested operations to creation and load of column and task
renamed FilesystemBoardManager
testing load all boards from a user directory
remove_data moved to a commons package
getting all the boards ids
testing save boards
created a module called operating_system to handle operations as create, remove folder files and serialise and deserialise objects
saving board, some code refactored
loading boards
code cleaned
Merge branch 'persistence_definition' into develop

* persistence_definition:
  code cleaned
  loading boards
  saving board, some code refactored
  created a module called operating_system to handle operations as create, remove folder files and serialise and deserialise objects
  testing save boards
  getting all the boards ids
  remove_data moved to a commons package
  testing load all boards from a user directory
  renamed FilesystemBoardManager
  tested operations to creation and load of column and task
  the mock models are storing the UUID as string to avoid constantly doing cast
  to avoid duplicate code, loader and saver merged with the BoardManager
  defining new tests for save and load tasks
  column id is created internally, so it is possible to define two columns with the same name
  loader and saver moved to a package called filesystem
  saving columns
  defined a test to save and load a column