Add spring-aop to acl and contacts compile dependencies following changes for SEC-1390.

AopInfrastructureBean interface is now required.

acl/acl.gradle

@@ -3,6 +3,7 @@
 dependencies {
     compile project(':spring-security-core'),
             "net.sf.ehcache:ehcache:$ehcacheVersion",
+            "org.springframework:spring-aop:$springVersion",
             "org.springframework:spring-context:$springVersion",
             "org.springframework:spring-core:$springVersion",
             "org.springframework:spring-tx:$springVersion",

samples/contacts/contacts.gradle

@@ -7,6 +7,7 @@ dependencies {
     providedCompile 'javax.servlet:servlet-api:2.5@jar'
     compile project(':spring-security-core'),
             project(':spring-security-acl'),
+            "org.springframework:spring-aop:$springVersion",
             "org.springframework:spring-core:$springVersion",
             "org.springframework:spring-beans:$springVersion",
             "org.springframework:spring-context:$springVersion",