Added support for the switch operation.
Reverted changes to junit and mockito imports in the Observable class.
Removed synchronized block as per RxJava guidelines (6.7).
Moving "implementation detail" classes out of public API
Move blocking operators to BlockingObservable

- see https://github.com/Netflix/RxJava/issues/270 for background
Deprecating 'toObservable' duplications of 'from' methods
Migrating from 'toObservable' to 'from' and using toBlockingObservable() where needed
Rewrite concat operation to not block on subscribe

The concat operator previously blocked on calling subscribe until all the
sequences had finished. In quite some cases this results in unwanted (and
unexpected) behaviour, such as when prefixing an infinite Observable
with a fixed one, for example when using startWith (which calls concat):
someInputStream.startWith(123).subscribe(x -> print(x));
This statement will block indefinitely if the input stream is infinite. Also
on finite sequences it seems silly to have to wait for them to finish.

In this new approach the incoming observables are put into a queue, instead
of waiting for the whole sequence to finish. When the first observable
completes, the next one is taken from the queue and subscribed to, and so
on. The queue can be extended while processing the observables, and
onCompleted is only called when both the source of observables has completed
and all observables in the queue have been read.
Make unit test more deterministic
README on internal nature of rx.operators package
Switch operator should now propagate onError in subsequences.
Replaced tabs with spaces.
Add new unit test to cover infinite observable being the first sequence.
Revert "Add new unit test to cover infinite observable being the first sequence."

This reverts commit 658d824b9f632f79a2b29979a6dfbb1a0a925783.
Add new unit test to check for non-blocking.
Merge pull request #272 from benjchristensen/BlockingObservable

BlockingObservable
Merge pull request #273 from billyy/concat

Concat
Merge pull request #259 from michaeldejong/operation-switch

Added the switch operator to Observable