Reorganise & improve QC.Uni criteria.

Even if obvious there was no statement about the fact that tests must
pass. This change:
i) clearly states that and merges it with the automation requirement
ii) groups all the coverage-related criteria

Fixes #99

content/06.quality_criteria.md

@@ -280,19 +280,19 @@ Unit testing evaluates all the possible flows in the internal design of the code
 behavior becomes apparent. It is a key type of testing for early detection of failures in the
 development cycle.
 
-* **[QC.Uni01]** Minimum acceptable code coverage threshold **SHOULD** be 70%.
+* **[QC.Uni01]** Test cases **MUST** run successfully in an automated fashion.
 
-  * **[QC.Uni01.1]** Unit testing coverage **SHOULD** be higher for those sections of the code
-    identified as critical by the developers, such as units part of a security module.
+* **[QC.Uni02]** Test cases (units) **SHOULD** reside in the repository code but separated from the main code.
 
-  * **[QC.Uni01.2]** Unit testing coverage **MAY** be lower for external libraries or pieces of code
-    not maintained within the product’s code base.
+* **[QC.Uni03]** Minimum acceptable code coverage threshold **SHOULD** be 70%.
 
-* **[QC.Uni02]** Units **SHOULD** reside in the repository code but separated from the main code.
+  * **[QC.Uni03.1]** Unit testing coverage **SHOULD** be higher for those sections of the code
+    identified as critical by the developers, such as units part of a security module.
 
-* **[QC.Uni03]** Unit testing coverage **MUST** be checked on change basis.
+  * **[QC.Uni03.2]** Unit testing coverage **MAY** be lower for external libraries or pieces of code
+    not maintained within the product’s code base.
 
-* **[QC.Uni04]** Unit testing coverage **MUST** be automated.
+  * **[QC.Uni03.3]** Unit testing coverage **MUST** be checked on change basis.
 
 ### 4.3.3. Test Harness [QC.Har]