rename "processors" -> "parsers"
add temporary-notes/ directory to .gitignore

Reason: temporary-notes/ directory will be used for ... temporary notes.
modify Main route handler module

Notable changes: when submitted to `extend`, it will now create some constants in the application class, which can be used to store "static" values.
fix up: rename "processors" -> "parsers"
add a workaround for Ruby before 2.1