Made Crypto an injectable component

Since this isn't a major component (the Play documentation doesn't
mention it) I didn't worry about breaking the Java API (the methods are
no longer static).

Also introduced a SimpleInjector implementation, that is map based, and
put Crypto in that for the default compile time dependency injection
components - since this is now the method that Crypto is looked up by,
for example when validating the session.
Merge pull request #3391 from jroper/crypto-inject

Made Crypto an injectable component
Add update to ExampleSSLConfig.md
Merge pull request #3394 from wsargent/add_client_auth_to_ws

[doc] Add update to ExampleSSLConfig.md
Fix example so it is clear the secure defaults should always be used.
Experimental Akka HTTP server backend and Reactive Streams integration

Introduces two new experimental libraries:
- play-akka-http-server-experimental
- play-streams-experimental

These libraries are built against Akka HTTP 0.6 and Reactive Streams
0.4.0.M1.

See the new *.md docs for more information.
Updated Akka HTTP link in docs
Merge pull request #3332 from richdougherty/akka-http-and-reactive-streams

Experimental Akka HTTP server backend and Reactive Streams integration