Use snapshot for cache insertion

Too many parallel attempts to insert the same keys can result in
`{erlfdb_error, 1020}`, which translates to:
"Transaction not committed due to conflict with another transaction"

This attempts to mitigate the problem by using a snapshot to read the
primary key during insertion.

convert erlfdb_error 2101 to transaction_too_large

convert erlfdb_error 2101 to transaction_too_large (apache#3215)

Use JSON collation

Fix include directive

Print stack if name and stack of exception are present

Version 3.1.1

Version 3.1.1-RC2

Version 3.1.1-RC1

Fix missing Content-Type in buffered responses

It turns out the "application/json" header is added downstream of the
delayed response's StartFun which is skipped for buffered responses.
This adds those headers back into the response.