Created models for Metric

Signed off by: Rafael Reggiani Manzo <rr.manzo@gmail.com>
Created Metric Configuration controller and model

Signed off by: Rafael Reggiani Manzo <rr.manzo@gmail.com>
Signed-off-by: Daniel Alves <danpaulalves@gmail.com>
Implemented metric_configurations_of and required changes to kalibro
configuration

Signed-off-by: Daniel Alves <danpaulalves@gmail.com>
Implemented test for metric_configurations_of

Signed-off-by: Daniel Alves <danpaulalves@gmail.com>
Added test for metric configuration association

Signed-off-by: Daniel Alves <danpaulalves@gmail.com>
Removed unused factories and kalibro configuration acessor
Achieving 100% test coverage

Signed off by: Rafael Reggiani Manzo <rr.manzo@gmail.com>
Merge pull request #6 from mezuro/metric_configuration

Metric configuration