Initialize gitignore.

.gitignore

@@ -0,0 +1,19 @@
+# See https://help.github.com/articles/ignoring-files for more about ignoring files.
+#
+# If you find yourself ignoring temporary files generated by your text editor
+# or operating system, you probably want to add a global ignore instead:
+#   git config --global core.excludesfile '~/.gitignore_global'
+
+# Ignore bundler config.
+/.bundle
+
+# Ignore all logfiles and tempfiles.
+/log/*
+/tmp/*
+!/log/.keep
+!/tmp/.keep
+/config/*.yml
+!/config/*.example.yml
+
+# Ignore Byebug command history file.
+.byebug_history