Fix CSV analysis

[artfuldev]

Fix #24

In this PR, we primarily fix #24. We do this by:

• introducing a new CSV analyzer engine that just treats it as text,
• providing the text in a better context for the analyzer to work better, and
• capturing the indices and transforming them to work for the text (we get indices for the cell, we fix it for the file)

In addition, we

• make stdio the only way to interact with the CLI
• fix the documentation
• add documentation for the --csv mode
• fix the app tests for /analyze endpoint
• skip the app tests for /anonymize endpoint (more changes are needed to the API)

Sample usage:

$ cat sample_data.csv
id,name,city,comments
1,Sowmya,New York,called him yesterday to confirm he requested to call back in 2 days
2,Jill,Los Angeles,accepted the offer license number AC432223
3,Jack,Chicago,need to call him at phone number 212-555-5555

$ cat sample_data.csv | pii analyze --csv | pii anonymize | jq -r '.text'
id,name,city,comments
1,<PERSON>,<LOCATION>,called him yesterday to confirm he requested to call back in 2 days
2,<PERSON>,<LOCATION>,accepted the offer license number <US_DRIVER_LICENSE>
3,<PERSON>,<LOCATION>,need to call him at phone number <PHONE_NUMBER>