Make REST API return and accept model boolean attributes as true/false instead of 't'/'f'

[kazlauskis]

The REST API interface returns and accepts boolean values as 't' or 'f' instead of true or false. To differentiate these values from regular text attributes, clients need to maintain a list of all the warehouse core boolean attributes and convert them from 't' or 'f' to true or false when communicating with the warehouse.

[johnvanbreda]

I can make the REST API accept true and false as alternatives to 't' & 'f'. However if I change the values that are returned is there a risk that will break things in apps and other things using the API?

[johnvanbreda]

The REST API will accept 't', true, 'f' or FALSE but currently still returns 't' and 'f'.

[kazlauskis]

My apps mostly use custom reports and ES indexes to ingest data, so I don't think it would break anything on my side, but I don't know about other projects. Allowing true/false for POST is a good start.

There is a growing need for the apps to do two-way sync with the warehouse and, unlike for reports, I would prefer raw REST API instead of ElasticSearch for this.

Links to #520