Update appveyor configuration

Author: acoburn

.appveyor.yml

@@ -1,26 +1,16 @@
 version: '{build}'
 skip_tags: true
-
-install:
-    - cinst jdk10 -params 'installdir=C:\\jdk10'
+skip_branch_with_pr: true
 
 build_script:
-    - gradlew.bat assemble
+    - appveyor-retry gradlew.bat assemble
 
 test_script:
-    - gradlew.bat check
+    - appveyor-retry gradlew.bat check
 
 environment:
     matrix:
         - JAVA_HOME: C:\Program Files\Java\jdk1.8.0
-        - JAVA_HOME: C:\jdk10
-
-cache:
-    - C:\Users\appveyor\.gradle\caches -> .gradle-wrapper\gradle-wrapper.properties
-    - C:\Users\appveyor\.gradle\wrapper -> .gradle-wrapper\gradle-wrapper.properties
-    - C:\Users\appveyor\.m2\wrapper -> .mvn\wrapper\maven-wrapper.properties
-    - cnf\cache\stable
-    - maven\target\m2
 
 matrix:
     fast_finish: true