Specify NLTK data directory in Dockerfile and add build test

[jinkjonks]

Description of the change

• Specify NLTK data directory in Dockerfile when running downloaders for punkt and stopwords.
• add a docker build smoke test (sleep at 20s because that seems to be how long it takes to boot up the jar)

Type of change

• Bug fix (non-breaking change that fixes an issue)
• New feature (non-breaking change that adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)

Related issues

• Fixes NLTK Data directory not found #85

Checklists

Development

• Lint rules pass locally
• The code changed/added as part of this pull request has been covered with tests
• All tests related to the changed code pass in development

Code review

• This pull request has a descriptive title and information useful to a reviewer. There may be a screenshot or screencast attached
• "Ready for review" label attached to the PR and reviewers mentioned in a comment
• Changes have been reviewed by at least one other engineer
• Issue from task tracker has a link to this pull request

[jinkjonks]

@ansukla @kiran-nlmatics Please review, thanks!

[jinkjonks]

Hey @jamesvillarrubia, I've noticed that you've been somewhat active. Can you please take a look at merging this? Cheers!