build: setup pre commit hook to check java format

* updates gradle wrapper to latest version to enable ghooks to be used.
* enables ghooks plugin for gradle
* adds google java format pre commit hook
* adds test check file output to gitignore

resolves openequella#25

.githooks/pre-commit

@@ -0,0 +1,11 @@
+#!/bin/sh
+#
+# An example hook script to verify proper formatting.
+
+files=$(git diff --cached --name-only --diff-filter=ACM | paste -s -d",")
+# this only works if ignoreFailures is set to false (which it is by default)
+./gradlew verifyGJF -DverifyGoogleJavaFormat.include="$files" &>/dev/null && exit 0
+
+echo "Some files are not formatted properly. Please run:"
+echo "./gradlew gJF -DgoogleJavaFormat.include=\"$files\""
+exit 1

.gitignore

@@ -16,3 +16,4 @@ test*.properties
 test*.xml
 *.log
 !src/test/**/*.log
+test-check-files-output/

build.gradle

@@ -1,5 +1,6 @@
 plugins {
 	id 'com.github.sherter.google-java-format' version '0.8'
+	id 'com.gtramontina.ghooks.gradle' version '1.1.0'
 }
 
 apply plugin: 'eclipse'

gradle/wrapper/gradle-wrapper.properties

@@ -1,6 +1,6 @@
-#Fri Jul 12 11:19:13 CDT 2019
+#Tue Jun 09 16:59:18 MST 2020
 distributionBase=GRADLE_USER_HOME
 distributionPath=wrapper/dists
 zipStoreBase=GRADLE_USER_HOME
 zipStorePath=wrapper/dists
-distributionUrl=https\://services.gradle.org/distributions/gradle-3.5-bin.zip
+distributionUrl=https\://services.gradle.org/distributions/gradle-6.5-bin.zip