Upgrade to Realm 3.x

[Zhuinden]

I don't want this example to be updated to Realm 2.x yet, until the following are fixed / merged:

• https://github.com/realm/realm-java/issues/3735 and https://github.com/realm/realm-java/issues/3858

• https://github.com/realm/realm-java/issues/3802

• https://github.com/realm/realm-java/issues/3804 (optional)

• https://github.com/realm/realm-java/issues/3651

• https://github.com/realm/realm-java/pull/3834

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Basically:

• ObjectStore Results integration (because I think it fixes a bunch of their current bugs)

• BlackBerry compatibility fix

• Samsung Tab 3 Lite 8 fix

• maybe fine-grained notification after Results integration because of https://github.com/realm/realm-java/issues/3427

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Until then, I'm keeping this example at 1.2.0

[Zhuinden]

Will be fixed by https://github.com/Zhuinden/realm-book-example/pull/7

[Zhuinden]

Will update to 3.x after https://github.com/realm/realm-java/pull/4402 is merged/released.

[Zhuinden]

Also need to fix https://github.com/realm/realm-java/issues/4437

[Zhuinden]

All bugs are now fixed in Realm 3.1.2