Use roman page numbers for preface

From the bug report "the front matter is roman numerals, and ends with
iii, but then goes to page 4 for the Overview containing the xi:included
Document change history, then goes to page 1 for the next chapter"

Now the preface uses roman numerals as well.

Change-Id: Ie9b0c5590c0f25f9f85a3400a114bafebec2a054
Closes-Bug: #1228314
Merge "Use roman page numbers for preface"