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-aop/spring-aop.gradle

@@ -0,0 +1,9 @@
+description = "Spring AOP"
+
+dependencies {
+	compile(project(":spring-beans"))
+	compile(project(':spring-core'))
+	optional("org.aspectj:aspectjweaver:${aspectjVersion}")
+	optional("org.apache.commons:commons-pool2:2.4.2")
+	optional("com.jamonapi:jamon:2.81")
+}