Make container-interop a suggested feature

Not everyone will use lazy listeners. As such, they will need to opt-in by
adding container-interop to their project.

Author: weierophinney

composer.json

@@ -29,16 +29,17 @@
         }
     },
     "require": {
-        "php": ">=5.5",
-        "container-interop/container-interop": "dev-master"
+        "php": ">=5.5"
     },
     "require-dev": {
         "phpunit/PHPUnit": "~4.0",
         "athletic/athletic": "^0.1",
         "squizlabs/php_codesniffer": "^2.0@dev",
-        "zendframework/zend-stdlib": "^2.7.3"
+        "zendframework/zend-stdlib": "^2.7.3",
+        "container-interop/container-interop": "^1.1.0"
     },
     "suggest": {
-        "zendframework/zend-stdlib": "^2.7.3, if using the FilterChain feature"
+        "container-interop/container-interop": "^1.1.0, to use the lazy listeners feature",
+        "zendframework/zend-stdlib": "^2.7.3, to use the FilterChain feature"
     }
 }

doc/book/intercepting-filters.md

@@ -9,6 +9,15 @@ take the incoming arguments in order to alter the workflow.
 zend-eventmanager provides an intercepting filter implementation via
 `Zend\EventManager\FilterChain`.
 
+## Preparation
+
+To use the `FilterChain` implementation, you will need to install zend-stdlib,
+if you have not already:
+
+```bash
+$ composer require zendframework/zend-stdlib
+```
+
 ## FilterChainInterface
 
 `Zend\EventManager\FilterChain` is a concrete implementation of

doc/book/lazy-listeners/intro.md

@@ -14,3 +14,12 @@ The feature consists of three classes:
 - `Zend\EventManager\LazyListenerAggregate`, which can take a list of
   `LazyEventListeners` and/or their definitions, and be used as an aggregate
   listener for attaching the lazy listeners to an event manager.
+
+## Preparation
+
+In order to use the lazy listeners feature, you will need to install
+container-interop, if you haven't already:
+
+```bash
+$ composer require container-interop/container-interop
+```