Make recording and scanning data more determined

HBase may contain only strings and unicodes.
In current implementation some entries put to db after str() or unicode(),
others are not being modified at all.
It is needed to make this process more determined. It may be achived by
creating serialize() and deserialized() methods. In these methods json library
may be used for safe work with HBase.

Partially implements bp hbase-alarming

Change-Id: If67a103e1d79d98cc93b88fe60e79c97fd17bb96
Removed global state modification by api test

This line caused 200 tests to fail in case of running tests with
unittest runner:
tox -e venv "python -m unittest discover -t . ceilometer/tests"

Change-Id: Ib4586e31061de91cc56c0186fe057473616d1776
Merge "Make recording and scanning data more determined"
Merge "Removed global state modification by api test"