Update requirements to latest versions

Ensure latest version of all required Python packages are used.
Update TwoSlug URL in README

Direct links to TwoSlug towards twoslug.aaroniles.net.
Refactor application from module to package

Change TwoSlug from being a module to a Python package.
Create simple applicatoin runner

Add simple script with command line options for launching the TwoSlug
application using the development server.
Factor out views and wordnet code into modules

Separate the Flask views and Wordnet API code into separate modules
inside the package.