Notifications: BUG_11 - TemplateRegexRelation

- repaired cyclic call of saveTemplateRegexRelation and
  updatePerunNotifTemplate by adding new method assignTemplateToRegex, which is now called from both methods
- repaired wrong removing TemplateRegexRelation by creating new method
  removeTemplateFromRegex
- edited parseMapWithList, so as it doesn't throw unnecessary exceptions