Content type redesign

Fixes #992, #1050, #1051, #1052

Adding custom jackson converter with some tests
Adds kryo message converter to replace codec
Checkstyle changes

Removing codec support
- Removed codec dependency from AbstractBinder
- MessageSerializationUtils is almost an empty shell for now, just to
  keep code compiling until we get EmbeddedHeaders interceptors
- Updated Kryo tests

Removing codec module from build
Added a new Annotation for custom converters '@StreamConverter'
Fixed some tests with new expected behavior
Moved broken tests to a temporary package to keep track of progress
Fixed KryoConverter to fail based on headers
Fixed a couple of more tests

Making converters strict to only convert their corresponding contentType
Bypassing conversion for ErrorMessages

* Configuring SI ConfigurableCompositeMessageConverter
 - Moved ContentType related beans into separate configuration
 - Configured SI ConfigurableCompositeMessageConverter to use same
   converters as Stream does (for ServiceActivator)
- TupleConverter should return byte[] as all other converters
- Fixed tests

* Fixes tests
 - Revert to Boot 2.0.0.M3. Snapshots breaking actuator
 - Checkstyle fixes
 - Disable JsonUnmarshalling as a catch all converter

Fixing Schema tests
Fixing Metrics tests
Fixing reactive tests
applying checkstyle fixes

 * Adding new content type tests
 - Fixed ContentTypeInterceptor misusage of default mimeType

Changing contentType doc section
Improving doc section
Last minute polish
Fixing BinderTests to use bytes to compare messages
Applied changes to Base Binders test to use the new contentType handling mechanism
PR review fixes

Renaming StreamConverter -> StreamMessageConverter

spring-cloud-stream-tools/src/main/resources/checkstyle.xml

@@ -99,14 +99,15 @@
             <property name="illegalPkgs" value="org.slf4j"/>
         </module>
         <module name="RedundantImport"/>
-        <module name="ReturnCount">
-            <property name="max" value="0"/>
-            <property name="tokens" value="CTOR_DEF"/>
-        </module>
         <module name="ReturnCount">
             <property name="max" value="1"/>
             <property name="tokens" value="LAMBDA"/>
         </module>
+        <module name="ReturnCount">
+            <property name="max" value="1"/>
+            <property name="tokens" value="CTOR_DEF"/>
+        </module>
+
         <!--
         <module name="ReturnCount">
             <property name="max" value="3"/>