This reverts commit efbe327f, reversing
changes made to 6d9bcd07.

We have contexts.hash_id which is enough (computed by postgres as a
trigger).

Test failed, not merging.

This reverts commit 2e77bfa5, reversing
changes made to fe201115.

When user searched for a phrase with space inside, in database, the
'to_tsquery' function raised an sql error. One should use
'plainto_tsquery'. Also, a proper test was added.

Get rid of that TVar completely.

It also improves the error in case it's the first time we are running
the tests and we have no coreNLP service running.

This commit adds a `panicTrace` function to be used as a drop-in
replacement of the `panic` function, with the difference that we
wrap the error in a `WithStacktrace` error, to be later caught
and logged.

This commit modifies the backend code to convert the input CSV into an
`NgramsList`, so that we can reuse the JSON API for the upload.

it also brings the CSV and JSON APIs closer in look.
Temporarily disable the `importCsvFile` function.

This commit makes possible to pass an optional `X-Garg-Error-Scheme`
header in a client request to enable the new error format.

It was only for test for now.

Added more tests for more subtle cases.