Allow non-numeric values to be chosen and confirmed

[codescape]

Ignore coffee and question strings and allow all other values to be assigned.

Tasks

• [x] calculate need to talk flag correctly
• [x] allow to persist non numeric values into custom fields
• [x] validate configuration and return non-assignable values

Out of scope

• 112

[codescape]

Inspiration

• https://bitbucket.org/tngtech-atlassian-add-ons/barcharts-for-jira/pull-requests/5/support-derived-custom-fields-by-checking/diff

Snippets

    CustomField customField = estimationFieldService.findStoryPointField();
    try {
        System.out.println("CustomField " + customField);
        // CustomField Story-Punkte
        System.out.println("CustomFieldType " + customField.getCustomFieldType());
        // CustomFieldType com.atlassian.jira.issue.customfields.impl.NumberCFType@13bf74e9
    } catch (Exception ignore) { }