doc(engine): fix javadoc by adding missing parameter documentation
feat(engine-rest/engine): Extend TaskRestService and TaskService

GET /task/{id}/comment
    returns all comments for task

GET /task/{id}/comment/{commentId}
    returns particular comment for task

POST /task/{id}/comment/create
    add comment for task and return comment object with link for the
    request

- extend engine task service to get particular comment for task id and
  comment id
- change addComment method from return value 'void' to 'Comment'
- add test cases

related to #CAM-2134, #CAM-2135, #CAM-2148
chore(engine-rest): Fix testcase

related to #CAM-2148
fix(engine/test): Fix testcase for history level none

related to #CAM-2148
fix(engine): handle null values of add comment command

related to #CAM-2167
fix(engine): add task in event subprocess to correct parent execution

related to #CAM-2155
impr(engine): get history level with management service

related to #CAM-2168
impr(engine-rest): improve task comment resources implementation

related to #CAM-2134, #CAM-2135 and #CAM-2148
Merge pull request #78 from tobiasschaefer/FixJavadoc

doc(engine): fix javadoc by adding missing parameter documentation
fix(engine): add update incident to mybatis configuration

- add revision to incident
- add update statement to incident mapping
- add revision column to database create and upgrade scripts

related to #CAM-2124
feat(engine-rest/engine): Add attachment methods to TaskRestService

GET /task/{id}/attachment
    returns all attachments for a task

GET /task/{id}/attachment/{attachmentId}
    returns particular attachment for a task

GET /task/{id}/attachment/{attachmentId}/data
    returns content for an attachment of a task

DELETE /task/{id}/attachment/{attachmentId}
    delete a particular attachment of a task

POST /task/{id}/attachment
    add attachment to a task and return attachment object with link for
    the request

- add new command to get task attachment for task id and attachment id in
  with usage in engine task service
- add new command to get task attachment content for task id and
  attachment id with usage in engine task service
- add  new command to delete task attachment for task id and attachment id
  with usage in engine task service

- add testcases for TaskRestService and TaskService

related to #CAM-2136, #CAM-2137, #CAM-2138, #CAM-2139, #CAM-2140