Bump version to 3.2.0.BUILD-SNAPSHOT, allow skipping of japicmp

In the future, in case a breaking API change is introduced on the road
to 3.2.0.RELEASE, the special `compatibleVersion` `SKIP` can be used to
circumvent the japicmp check.

build.gradle

@@ -256,13 +256,16 @@ project('reactor-core') {
 			"org.mockito:mockito-core:$mockitoVersion",
 			"org.openjdk.jol:jol-core:0.9"
 
-	baseline("io.projectreactor:reactor-core:$compatibleVersion") {
-	  transitive = false
-	  force = true
+	if ("$compatibleVersion" != "SKIP") {
+	  baseline("io.projectreactor:reactor-core:$compatibleVersion") {
+		transitive = false
+		force = true
+	  }
 	}
   }
 
   task japicmp(type: JapicmpTask) {
+	onlyIf { "$compatibleVersion" != "SKIP" }
 	oldClasspath = configurations.baseline
 	newClasspath = files(jar.archivePath)
 	onlyBinaryIncompatibleModified = true
@@ -428,13 +431,16 @@ project('reactor-test') {
 			"org.assertj:assertj-core:$assertJVersion",
 			"org.mockito:mockito-core:$mockitoVersion"
 
-	baseline("io.projectreactor:reactor-test:$compatibleVersion") {
-	  transitive = false
-	  force = true
+	if ("$compatibleVersion" != "SKIP") {
+	  baseline("io.projectreactor:reactor-test:$compatibleVersion") {
+		transitive = false
+		force = true
+	  }
 	}
   }
 
   task japicmp(type: JapicmpTask) {
+	onlyIf { "$compatibleVersion" != "SKIP" }
 	oldClasspath = configurations.baseline
 	newClasspath = files(jar.archivePath)
 	onlyBinaryIncompatibleModified = true

gradle.properties

@@ -1,2 +1,2 @@
-version=3.1.5.BUILD-SNAPSHOT
+version=3.2.0.BUILD-SNAPSHOT
 compatibleVersion=3.1.4.RELEASE