Fixed UnitTest bugs

When BucketOutputBlock was introduced in commit
9a723ee6248809441ac047515a3345262043b563, it put a
level of indirection between GraphiteLineOutputBlock
and the tests. This commit fixes the unit tests based
on the redirection.

"sumSquares" aggregations where introduced in the same
commit. This commit adds verification of "sumSquares"
values.
Use passed in dateTime in ControllableIntervalService.Pulse(DateTime?)

Fixes a bug introduced in 8a7fde0e5ccafa435ce62e2125cc26a5e7a0cd73
Merge pull request #34 from tedoc2000/unittest-fixes

Unittest fixes