Support Jinja in option "mapping"

[iSOLveIT]

The feature will allow the mappings option to accept more complex scenarios for the option value. For Instance:

• static value: - e.g. "spec"
• dynamic value (coming from excel): - e.g. "{{status}}"
• static and dynamicvalue: - e.g. `"is{{status}}"or"{{status}}_issue"`
• multiple dynamic values + static: - e.g. "{{title}}_{{id}}_{{assignee}}"

Tasks

• [x] Implement Jinja support
• [x] Make values from the excel row available in the jinja context
• [ ] Document this feature and some simple and complex examples