Update Java dependencies

Update most dependencies to their latest versions, replace findbugs with
spotbugs as the former is dead and was replaced with the latter.

Fixes THRIFT-4937.

Client: java
diff --git a/lib/java/gradle.properties b/lib/java/gradle.properties
index c5d2a1b..8559464 100644
--- a/lib/java/gradle.properties
+++ b/lib/java/gradle.properties
@@ -25,10 +25,10 @@
 maven-repository-id=apache.releases.https
 
 # Dependency versions
-httpclient.version=4.5.6
-httpcore.version=4.4.1
-slf4j.version=1.7.25
+httpclient.version=4.5.10
+httpcore.version=4.4.12
+slf4j.version=1.7.28
 servlet.version=2.5
 junit.version=4.12
-mockito.version=1.9.5
+mockito.version=1.10.19
 javax.annotation.version=1.3.2