add .gitignore

.gitignore

+target
+
+# Compiled class file
+*.class
+
+# Log file
+*.log
+
+# BlueJ files
+*.ctxt
+
+# Mobile Tools for Java (J2ME)
+.mtj.tmp/
+
+# Package Files #
+*.jar
+*.war
+*.ear
+*.zip
+*.tar.gz
+*.rar
+
+# virtual machine crash logs, see http://www.java.com/en/download/help/error_hotspot.xml
+hs_err_pid*
+
+#IDE metadata
+**.idea/**
+.idea/
+*.iml
+
+# Eclipse
+.project
+.classpath
+.settings
+
+#updatebot checkout dir
+.updatebot-repos/
+.updatebot-repos/**
\ No newline at end of file