Fix access to 'clock' member in ColumnFamilyTemplate hierarchy

[zznate]

Currently unsafe and inconsistent.

Proposal is to push the clock into the Updater based on the configured clock type every time an updater is constructed. the Updater will add the ability to set the clock to override the automatically constructed value.

This will deprecate the following methods on AbstractColumnFamilyTemplate:
setClock
getEffectiveClock

The following method will change behavior on AbstractColumnFamilyTemplate:
getClock - will simply wrap the value returned by Keyspace#createClock