Add get_corpus_default_db and thainer 1.5 model

[wannaphong]

What does this changes

Add get_corpus_default_db and thainer 1.5 model

What was wrong

Now, You can add corpus on default_db,json and you dont load last thainer model from Internet.

How this fixes it

Description of how the changes fix the issue.

Fixes #575 #298

Your checklist for this pull request

🚨Please review the guidelines for contributing to this repository.

• Passed code styles and structures
• Passed code linting checks and unit test

[pep8speaks]

Hello @wannaphong! Thanks for updating this PR. We checked the lines you've touched for PEP 8 issues, and found:

There are currently no PEP 8 issues detected in this Pull Request. Cheers! 🍻

Comment last updated at 2021-06-01 17:30:28 UTC

[coveralls]

Coverage decreased (-0.01%) to 95.961% when pulling 0895ab7 on add-thainer-model into ab888cc on dev.

[bact]

May need test for get_corpus_default_db()

• what if name or version is None or not found?

[wannaphong]

May need test for get_corpus_default_db()

* what if `name` or `version` is None or not found?

The load model function maybe failed. I used it in get_corpus_path function.