Add annotation tests for compartments

[matthiaskoenig]

Problem description

compartments are an important part of constraint-based models. Correct annotation and description of compartments is important to evaluate the quality of the model and understand the model content. Currently, in memote no tests for annotations on compartments are performed (such tests should be analogue to the annotation tests for reactions, metabolites or genes).

This issue depends on correct representation of compartments in cobrapy which would allow to access the annotations. See opencobra/cobrapy#760.