Add .gitignore file to theme boilerplate

.gitignore

@@ -0,0 +1,67 @@
+# WordPress
+wp-config.php
+wp-content/uploads/
+wp-content/blogs.dir/
+wp-content/upgrade/
+wp-content/backup-db/
+wp-content/cache/
+wp-content/backups/
+
+# Theme build files
+*.css.map
+*.js.map
+
+# Dependencies
+node_modules/
+vendor/
+bower_components/
+
+# IDE and editor files
+.vscode/
+.idea/
+*.sublime-project
+*.sublime-workspace
+*.swp
+*.swo
+*~
+.project
+.settings/
+.buildpath
+
+# OS generated files
+.DS_Store
+.DS_Store?
+._*
+.Spotlight-V100
+.Trashes
+ehthumbs.db
+Thumbs.db
+Desktop.ini
+
+# Log files
+*.log
+npm-debug.log*
+yarn-debug.log*
+yarn-error.log*
+
+# Package manager files
+package-lock.json
+yarn.lock
+composer.lock
+
+# Build directories
+dist/
+build/
+.sass-cache/
+.cache/
+
+# Environment variables
+.env
+.env.local
+.env.*.local
+
+# Temporary files
+*.tmp
+*.temp
+.tmp/
+.temp/