Move modules to independent build files

The main `build.gradle` file contains now only the common build
infrastructure; all module-specific build configurations have
been moved to their own build file.

Issue: SPR-15885

spring-tx/spring-tx.gradle

@@ -0,0 +1,16 @@
+description = "Spring Transaction"
+
+dependencies {
+	compile(project(":spring-beans"))
+	compile(project(":spring-core"))
+	optional(project(":spring-aop"))
+	optional(project(":spring-context"))  // for JCA, @EnableTransactionManagement
+	optional("javax.ejb:javax.ejb-api:3.2")
+	optional("javax.interceptor:javax.interceptor-api:1.2")
+	optional("javax.resource:javax.resource-api:1.7")
+	optional("javax.transaction:javax.transaction-api:1.2")
+	optional("com.ibm.websphere:uow:6.0.2.17")
+	testCompile("org.aspectj:aspectjweaver:${aspectjVersion}")
+	testCompile("org.codehaus.groovy:groovy-all:${groovyVersion}")
+	testCompile("org.eclipse.persistence:javax.persistence:2.1.1")
+}