Commit contains all backend tasks for the eigth sprint.

The focus of sprint 8 was to:

- enhance response text configuration with negative responses
- add interface for dashboard statement requests
- add archive functionality to persist the statement after process
  is finished
- add authorization configuration and rules
- add customerReference and creationDate to statements
- enhance howToBuild and howToRun documentation

Details:

[TOB-292] doc: howToBuild and howToRun

* enhanced the howToBuild and howToRun documentation
* added sections how to build and configure the front end
* added sections how to configure the back end

[TOB-381] fix: dasshboard editedByMe

* fixed logic of the editedByMe boolean of the dashboard statement
  response. Verifies if there's an editLogEntry for the statement
  for the current username.

[TOB-54] feat: archive finished statements

* added archive feature. When finishing a statement a folder with a
  configurable name-template is created. Attachments of with no outbox
  tag are stored in a info-data subfolder. Outbox attachments such as
  the statement response and other uploaded attachments are stored in a
  sent-data subfolder. This is either triggered when a statement was
  successfully sent as an email or by manyally triggering the finish
  REST interface.

[TOB-389] feat: create statement invalid contact

* added the specific 422 response status code on create and update
  statement interfaces in case the provided contactsId is not valid.

[TOB-381] feat: dashboard statement interface

* added dashboard/statement REST interface
* added editLogs to database on create statement and claim statement
  task
* added authorization rules for dashboard interface access and mail
  interface
* added unittests for the new dashboard interface and editLogs
* added additional uinittests for other services

[TOB-23] feat: negative response textblocks

* enhance textblock configuration models and parsers with negativeGroups
* update sample textblock config in database
* create valid authorization config and rules for negative response
  workflow

[TOB-350,351,352] statement reference info

* enhanced REST interface model statement
* added creationDate
* added customerReference
* added creationDate, customerReference, statementId and currentDate as
  new place holder values for response PDF generation
* removed duplicate model class StatementModel and replaced it with the
  already existing StatementDetailsModel that had the same fields

[TOB-290] authorization logic

* edded authorization configuration file
* added authorize interface to the StatementAuthorizationService to
  verify actions against the configured rules
* added simple CSVReader helper to read csv files
* enhanced statement task list interface response with indicator if task
  could be claimed by current user including check for
  required_department users
* added some minor comments
* added testcases for new code

Signed-off-by: Tobias Stummer <stummer@develop-group.de>