- Updated CHANGELOG with latest changes

develop

Conflicts:
	src/main/java/org/ow2/authzforce/core/pdp/impl/PdpConfigurationParser.java

- POM: changed project version: 5.0.3-SNAPSHOT -> 6.0.0
- POM: changed dep version: authzforce-ce-core-pdp-api 7.1.2-SNAPSHOT ->
8.0.0-SNAPSHOT
- POM: added owasp-dependency-check plugin
- Replaced classes (Ordered)Deny/PermitOverridesCombiningAlg with
DPOverridesCombiningAlg
- Replaced classes Deny/PermitUnlessPermit/DenyCombiningAlg with
DPUnlessPDCombiningAlg 
- LogicalNOfFunction: first parameter (minimum of TRUE arguments to
return TRUE) checked at Apply parsing time if constant
- Substring function: second and third arguments checked at Apply
parsing time if constant (arg1 >= 0, arg2 == -1 || arg2 >= arg1)
- XACML Condition: expression checked whether constant FALSE -> illegal
(or TRUE -> optimized)
- Fixed issues with unit tests 

Update README with the address of the CII badge

Renamed class from *Alg to *CombiningAlg

first and ignore/remove useless rules, e.g. if one Deny/Permit rule is
empty)
- Condition optimization: pre-evaluation of condition's Expression at
initialization time to check whether the expression is not constant
True/False