Add findbugs reports, don't fail the build on them.

Change-Id: I9e52ff2493bf33e8f5e61f027e15505dc407d2cb
Reviewed-on: http://gerrit.dmdirc.com/3944
Reviewed-by: Greg Holmes <greg@dmdirc.com>
Automatic-Compile: DMDirc Build Manager

build.gradle

@@ -21,6 +21,7 @@ dependencies {
 
 allprojects {
     apply plugin: 'java'
+    apply plugin: 'findbugs'
     apply plugin: 'pmd'
 
     sourceSets {
@@ -61,6 +62,19 @@ allprojects {
         ruleSets = []
         ruleSetFiles = files("$rootDir/etc/pmd/full.xml")
     }
+
+    tasks.withType(FindBugs) {
+        reports {
+            html.enabled = true
+            xml.enabled = false
+        }
+    }
+
+    findbugs {
+        reportLevel = 'low'
+        effort = 'max'
+        ignoreFailures = true
+    }
 }
 
 task wrapper(type: Wrapper) {