Add .gitignore

Used a copy of .gitignore of mediawiki/core and removed some lines,
because in this extension not all the folders which are in core.

Change-Id: I37e2bb03143b3b8f388bcf44bdcd82ce2a2ac767

.gitignore

@@ -0,0 +1,43 @@
+# git-deploy status file:
+/.deploy
+
+# Editors
+*.kate-swp
+*~
+\#*#
+.#*
+.*.swp
+.project
+cscope.files
+cscope.out
+## NetBeans
+nbproject*
+project.index
+## Sublime
+sublime-*
+sftp-config.json
+
+# Building & testing
+node_modules/
+
+# Composer
+/vendor
+/composer.lock
+/composer.json
+
+# Operating systems
+## Mac OS X
+.DS_Store
+## Windows
+Thumbs.db
+
+# Misc
+.buildpath
+.classpath
+.idea
+.metadata*
+.settings
+/static*
+/tags
+/.htaccess
+/.htpasswd