Make entities (Resource, User, Project) able to store lists

When one Resource contains several meters we should store all of them.
The same is true about User, Project and Resource regarding sources.
To make it possible it is needed to change the way we store data in Hbase.

Now Resource, User and Project may contain several sources. Besides, Resource may contain several meters.
To store all of them we use ColumnFamily f and columns m_meters and s_sources.
All meters stored as JSON-ed list.
E.g.
resource_1: {f: {meters: [meter1, meter2, meter3]} }
The same for users and projects:
user_1: {f: [sources: [source_1, source_2]}

We cannot update these lists safely.

In this commit m_meters and s_sources are changed to m_{unique_meter_structure} and s_{unique_source_name}.
So we getting rid of 'lists' and may use safe put() method.
All meters in Resource and sources in User, Project, Resource are
stored with stub value=1 to make filtering simpler.

New ColumnFamilies are not introdused here because CF is a 'namespace' and make sence in case when
there is a lot of requests only for this CF. But it's not the case for Ceilometer: each request may
contain _id field or metadata filter. It's better to store all this info in one CF.

Closes bug 1288284

Change-Id: I5814202e3d59fd29f96c8734e445367f766e6a4a
Merge "Make entities (Resource, User, Project) able to store lists"