CORDA-2149 CorDapp Contract and Workflow version identifiers (#4363)

* Implementation of Contract and Workflow attribute identifiers.

* Fixes following rebase from master.

* Fix broken JUnit test.

* Fix broken JUnit test.

* Fix broken JUnit test.

* Added missing constants.

* Further clean-up.

* Updated documentation.

* Added changelog entry.

* Updated all samples (using new Gradle Plugin 4.0.37 functionality)

* Temporarily resolve gradle plugins from latest published snapshot.

* Temporarily resolve gradle plugins from latest published snapshot.

* Updates following feedback from PR review.

* Move constants into CordappInfo companion object.

* Contract and Workflow attribute `version` to `versionId` (as version is a reserved gradle variable)

* Clarified warning message on incorrect version identifier.

* Align version identifier processing logic with gradle cordapp plugin.

* Updated comment.

* Minor fixes following rebase from master.

* Fixed broken unit test.

* Improved exception reporting.

* Update to use 4.0.37 of Gradle Plugins.

* Added support for combined Contract and Workflow CorDapp info.

* Updated following discussions with Shams + cleanup.

* Updated following Shams PR review.

* Minor API improvements.

* Added missing cordapp info causing deployNodes to fail.

samples/trader-demo/build.gradle

@@ -140,10 +140,12 @@ jar {
 }
 
 cordapp {
-    info {
+    targetPlatformVersion corda_platform_version.toInteger()
+    minimumPlatformVersion 1
+    workflow {
         name "net/corda/samples/trader-demo"
-        vendor "Corda Open Source"
-        targetPlatformVersion corda_platform_version.toInteger()
-        minimumPlatformVersion 1
+        versionId 1
+        vendor "R3"
+        licence "Open Source (Apache 2)"
     }
 }