Add .gitreview config.

Change-Id: Iafec8c73d67dcf73aa34e5fcc450a4c4f8492db6
Reviewed-on: http://gerrit.dmdirc.com/4019
Reviewed-by: Greg Holmes <greg@dmdirc.com>
Automatic-Compile: DMDirc Build Manager

.gitreview

@@ -0,0 +1,5 @@
+[gerrit]
+host=dmdirc.com
+port=29418
+project=plugins
+defaultbranch=master