Dates conversion fixes

| Q                    | A
| -------------------- | ---
| Bug fix?             | Yes
| New feature?         | No
| BC breaks?           | No
| CI currently passes? | Yes
| Tests pass?          | Yes
| Scenarios pass?      | In progress
| Checkstyle issues?*  | No
| PMD issues?**        | No
| Changelog updated?   | Yes
| Fixed tickets        | PIM-2971
| Doc PR               | N.A.
It's a huge task and outside of the scope of this PR ;)

This fix was to avoid having date like that:
2014-07-29 06:15:23 (without AM or PM)
and now to have:
2014-07-29 18:15:23

So now the date is right, because the "h" format for date does not make sense without PM/AM.