Remove shared model deletion and enumeration specs

[#72664052]

Signed-off-by: Joseph Palermo <jpalermo@pivotallabs.com>
Add explicit tests for created_at and updated_at on models

[#72664052]

Signed-off-by: Joseph Palermo <jpalermo@pivotallabs.com>
New matchers to test associations work. Used in spaces_spec.

[#72664052]

Signed-off-by: Joseph Palermo <jpalermo@pivotallabs.com>