1.7.6: Persistent cache (#32)

* move deleteKey to cache interface

* use static cache for persistent connections, local cache for non-persistent

* add php73 to circle

* switch to rc

* connect to ephemeral

* remove socket on disconnect

* disconnect on retry

1.7.5: support count distinct (#31)

* support count distinct

* increase timeouts in cql tests

1.7.4: Aggregate fixes (#30)

* bugfix removeOrderBy

* select all fields from groupby

* ensure we still select fields if we are not grouped

* optimisation: select specified aggregate field

* improve tests and additional coverage

1.7.3

 * use subquery for grouped collections (#29)

* refactor code for clarity

1.7.2: fix aggregates with limit (#28)

* initialise daos array

* only remove ORDER BY clause with no LIMIT

* add php72

1.7.1

Fixed performance metrics properly (#27)

1.7.0: Return the result of each (#26)

* Return the result of each

* Return doc

1.6.1

Relax querybuilder requirements (#23)

1.6.0

Retrieve configuration on QL datastore and connection (#22)

1.5.1: MySQLi Improvements (#21)

* MySQLi Improvements

* Add close to failing raw