Updating an instance fails

Fixes #1082

This is related to the workaround put in for RAILS bug
https://github.com/rails/rails/issues/17466

The code was expecting all values to be present in the
ae_instance.ae_values, the import/export only add non-empty values.
The UI seems to add all values even if they are empty.
So in a new database after the import/export only non empty values are
present as soon as you save it in the DB all values get added by the UI.
If this is a issue we can open a separate git issue for it.
Avoid DOM id conflict by prefixing AE endpoint selection buttons.
Merge pull request #1078 from martinpovolny/automate_buttons

Automate endpoint miqButtons fix
Update CHANGELOG.md for Sprint 15

Add changes, removals, fixes, enhancements.
correct links to milestone Sprint 15 (the date end was changed)
Updated removed and changed sections per comments.
added UI bullet about I18N
Memoist gem bullet update

[skip ci]
Merge pull request #1035 from mfeifer/readme

Update CHANGELOG.md for Sprint 15
Merge pull request #1083 from mkanoor/git_issue_1082

Updating an instance fails