POST/PATCH file to API endpoint

[andrew-fenton]

Implemented and tested POST API endpoint to insert new translations into database.

Key points:

• Translations will not be added if translations data does not follow format:

"translations" : [
    {
        "language": "<language>",
         "<original_word>": "<translated_word>",
    },
    ...
]

• If any translations are being updated using a POST request, no translations will be added to the database. Use PATCH endpoint for updates instead.
• If any new translation insertion fails, no translations will be added to the database. All previously added translations will be rolled back.

Notes:

• When an insertion error occurs with one or more of the translations, we return status code 500. How do we deal with the error internally though? Logging?

[hriday330]

Excellent work on the translation file processing and tests