Pressing 'generate word' reloads the model/vocabulary each time

[annaproxy]

Pressing 'generate word' reloads the model/vocabulary each time

[Sasafrass]

We now have a session object which should be available globally with from flask import session. This can be used in similar fashion to a dictionary and should allow us to store and access a model in a single session without having to reload it each time.

[Sasafrass]

This is a little bit trickier than I initially thought. Storing the model in the session in the generate_slang function appears not to work. Possible causes:

• Storing a full PyTorch model or our own Vocabulary object in a session is not possible.
• The API call to /api/generate_slang results in a new session object to be instantiated, ignoring our stored session.
• Filesystem version of the session instead of the redis-server version.

Currently investigating the second option.

[Sasafrass]

The following PR should fix it: #52