Improve Docker setup (PR #497)

.dockerignore

@@ -1,12 +1,43 @@
 .git
-.idea
-.sass-cache
+.gitignore
+
+.bundle
+.rake_tasks*
+db/*.sqlite3
 log
-config/database.yml
-doc
+node_modules
+tmp/*
 public/assets
 public/system
-tmp/*
+public/uploads
 vendor/bundle
+
+# no configuration
+config/*.yml
+!config/i18n-js.yml
+
+# IDEs, Developer tools
+.idea
+.loadpath
+.project
+.sass-cache
+.rbenv-version
+.get-dump.yml
+.bash_history
+.localeapp
+nbproject/
+.*.sw?
+*~
+
 coverage
-*.sql*
+tags
+doc/app/
+doc/api/
+.yarddoc/
+rspec.failures
+
+# Capistrano etc.
+Capfile
+config/deploy
+config/deploy.rb
+Gemfile.capistrano*