Load fields to display for sub tasks from Jira configuration

[codescape]

The columns to be displayed for sub tasks can be configured globally inside Jira on the advanced settings page by the parameter called: jira.table.cols.subtasks

This configuration should be used to display the fields of the sub tasks inside the sub task table.

This feature request is extracted from a customer mail.

Tasks

• display all fields configured by the above parameter
• add styling for fields according to their content