Bump to Robolectric 2.3, make samples build under Studio 0.8.+

refs https://github.com/Netflix/RxJava/pull/1449
Fix issue #1522
Add operators to create Observables from BroadcastReceiver

it allows to listen global and local (with support LocalBroadcastManager) broadcasts
remove main thread unsubscribe, fix LocalBroadcastOperatorTest
fix sticky intent duplication, add tests for OperatorBroadcast
Optimize the fix for takeLast and handle the race condition
Fix the unbounded check for merge
Make "single" support backpressure

Signed-off-by: zsxwing <zsxwing@gmail.com>
Merge pull request #1530 from zsxwing/issue-merge

Fix the unbounded check for merge
Merge pull request #1523 from zsxwing/issue-1522

Fix issue #1522
Merge pull request #1528 from Yarikx/android-broadcasts-rebased

Add operators to create Observables from BroadcastReceiver (rebased)