Make gretty samples compatible with logback 1.2.9

Explicitly reference the logback.xml file to prevent gretty from configuring the defaults using groovy.

spring-session-samples/spring-session-sample-javaconfig-custom-cookie/spring-session-sample-javaconfig-custom-cookie.gradle

@@ -29,4 +29,5 @@ dependencies {
 
 gretty {
 	jvmArgs = ['-Dspring.profiles.active=embedded-redis']
+	logbackConfigFile = "src/main/resources/logback.xml"
 }

spring-session-samples/spring-session-sample-javaconfig-hazelcast/spring-session-sample-javaconfig-hazelcast.gradle

@@ -29,3 +29,7 @@ dependencies {
 	integrationTestCompile "org.seleniumhq.selenium:htmlunit-driver"
 	integrationTestCompile "org.seleniumhq.selenium:selenium-support"
 }
+
+gretty {
+	logbackConfigFile = "src/main/resources/logback.xml"
+}

spring-session-samples/spring-session-sample-javaconfig-jdbc/spring-session-sample-javaconfig-jdbc.gradle

@@ -25,3 +25,7 @@ dependencies {
 	integrationTestCompile "org.seleniumhq.selenium:htmlunit-driver"
 	integrationTestCompile "org.seleniumhq.selenium:selenium-support"
 }
+
+gretty {
+	logbackConfigFile = "src/main/resources/logback.xml"
+}

spring-session-samples/spring-session-sample-javaconfig-redis/spring-session-sample-javaconfig-redis.gradle

@@ -29,4 +29,5 @@ dependencies {
 
 gretty {
 	jvmArgs = ['-Dspring.profiles.active=embedded-redis']
+	logbackConfigFile = "src/main/resources/logback.xml"
 }

spring-session-samples/spring-session-sample-javaconfig-rest/spring-session-sample-javaconfig-rest.gradle

@@ -30,4 +30,5 @@ dependencies {
 gretty {
 	jvmArgs = ['-Dspring.profiles.active=embedded-redis']
 	servletContainer = 'tomcat9'
+	logbackConfigFile = "src/main/resources/logback.xml"
 }

spring-session-samples/spring-session-sample-javaconfig-security/spring-session-sample-javaconfig-security.gradle

@@ -33,4 +33,5 @@ dependencies {
 
 gretty {
 	jvmArgs = ['-Dspring.profiles.active=embedded-redis']
+	logbackConfigFile = "src/main/resources/logback.xml"
 }

spring-session-samples/spring-session-sample-misc-hazelcast/spring-session-sample-misc-hazelcast.gradle

@@ -24,3 +24,7 @@ dependencies {
 	integrationTestCompile "org.seleniumhq.selenium:htmlunit-driver"
 	integrationTestCompile "org.seleniumhq.selenium:selenium-support"
 }
+
+gretty {
+	logbackConfigFile = "src/main/resources/logback.xml"
+}

spring-session-samples/spring-session-sample-xml-jdbc/spring-session-sample-xml-jdbc.gradle

@@ -25,3 +25,7 @@ dependencies {
 	integrationTestCompile "org.seleniumhq.selenium:htmlunit-driver"
 	integrationTestCompile "org.seleniumhq.selenium:selenium-support"
 }
+
+gretty {
+	logbackConfigFile = "src/main/resources/logback.xml"
+}

spring-session-samples/spring-session-sample-xml-redis/spring-session-sample-xml-redis.gradle

@@ -29,4 +29,5 @@ dependencies {
 
 gretty {
 	jvmArgs = ['-Dspring.profiles.active=embedded-redis']
+	logbackConfigFile = "src/main/resources/logback.xml"
 }