Use moveLastOver instead of Remove

This is important especially in the light or recent changes in core.
It will also increase performance and fix potential problems with deletes and links.
Merge branch 'master' of github.com:realm/realm-java into ez-use-move-last-over
Update changelog, additional test
Update changelog.txt
Update RealmObjectTest.java
Merge pull request #562 from realm/ez-use-move-last-over

Use moveLastOver instead of Remove