build.gradle: Print failed tests a bit more detailed.

.travis.yml

@@ -8,7 +8,7 @@ jdk:
 install:
   - sudo apt-get install -y protobuf-compiler
 script:
-  - gradle -q clean check -x :wallettemplate:check
+  - gradle clean check -x :wallettemplate:check
 
 notifications:
   irc:

core/build.gradle

@@ -34,6 +34,10 @@ protobuf {
 
 test {
     exclude 'org/bitcoinj/net/NetworkAbstractionTests*'
+    testLogging {
+        events "failed"
+        exceptionFormat "full"
+    }
 }
 
 task javadocJar(type: Jar, dependsOn: javadoc) {