[openFATE 305844] osc changelog support

Feature changed by: Adrian Schröter (adrianSuSE) Feature #305844, revision 5 Title: osc changelog support Buildservice: Done Priority Requester: Mandatory Requested by: Adrian Schröter (adriansuse) - Developer: Peter Poeml (poeml) Description: We need changelog support in osc. A possible way to implement this can happen on submit request create: * Show all comments in commit history since last sr * Offer to edit them in editor * Offer extra lines for adding bugzilla and fate numbers and create correct syntax. -- openSUSE Feature: https://features.opensuse.org/305844