Create /src/perf for Performance Tests

- Move existing performance tests into this source folder.
- Not building via Gradle yet … I have yet to figure that part out.
Start of Performance Testing Operators

These are examples of how we should proceed. Very likely though we want to use something like Caliper: https://code.google.com/p/caliper/
Merge pull request #760 from benjchristensen/perf-tests

Performance Tests Source Folder
adding diagrams to javadocs for replay(selector) variants
adding javadoc marble diagram for the mergeMap(next,completed,error) variety
Merge pull request #762 from Netflix/docs

adding javadoc marble diagram for the mergeMap(next,completed,error) variety
A variety of improvements to the javadoc text.
Zip fix for multiple onCompleted and moved unsubscribe outside the lock.
Merge pull request #765 from Netflix/docs

A variety of improvements to the javadoc text.
Merge pull request #767 from akarnokd/ZipFixes

Zip fix for multiple onCompleted and moved unsubscribe outside the lock.
Added Observable.bind

- new create signature
- new bind operator
- new subscribe overload
- OperationReplay is failing unit tests, all others are passing
Re-implemented Take Operator with Bind

- also simplified implementation to not worry about thread-safety as per Rx contract
- performance improvement from 4,033,468 ops/sec -> 6,731,287 ops/sec
Bind implementation of fromIterable, toList, toSortedList
Bind implementation of Map, Cast, Timestamp
Take: Fix Terminal State Handling

- even though unit tests don’t see it because of SafeObserver, the Take operator should not emit onCompleted more than once
Bind implementation of Merge

- it’s working … but I can’t figure out the co/contra-variance for the generics! anyone have ideas?
New Bind Signature and GroupBy Operator

- Changed `bind` signature to match the variant discussed at https://github.com/Netflix/RxJava/issues/746#issuecomment-32711145
- Updated code to new signature.
- Re-implemented GroupBy operator with `bind`
Bind implementation of Parallel
Bugfix: GroupBy Completion

Found bug while doing Parallel. It was completing prematurely when child groups were asynchronous and delayed.
Operator Class

- forgot to add earlier