Appveyor badge

This version only prerelase since it'll do only netstandard

Removed the dnx451 block in project.json

RwLockSlim instead of ConcurrentDictionary

Ensures that MemBus can now also target WP8.

Roundup for release v3.0

- Removed Automaton and old projects (new test shows how to recreate
timer functionality from Rx
- New target for Nuget package
- version bump up

Check against adding a null subscription on CompositeSubscriber; Chec…

…k against race condition when using a DisposableSubscription that somebody is disposing.

Dead code removal; Version bump-up

Stuff to do with Nuget building

Version, nuspec update

Fix: Publishing subscription returning null without causing an exception