Add test coverage for *Clock and *Strategy

We introduced the lag strategies 'RelaxedStrategy' and 'StrictStrategy' without
test coverage. Additionally, the default tests did not cover the case of an
inconsistent slave, likely because the default strategy does not attempt to
deal with slave lag unles with_consistency is used.

We broke master_slave_adapter_spec into a spec per strategy. Each spec will use
as much of the shared behavior (spec/common/support/strategies/default),
as possible.

TODO (grep for TODO):
  * fixup integration tests (or fixup clock interface)

Change-Id: I536803f92af32c837c36797edf6516ec2172562b
Reviewed-on: https://gerrit.causes.com/17349
Reviewed-by: John Skopis <john.skopis@causes.com>
Tested-by: John Skopis <john.skopis@causes.com>