Move to CompoundConditionBuilder

Build a compound condition as the combination of two or
more conditions linked by a logical operator.
Add ConditionBuilderStrategyFinder
Add ValueConditionBuilder

- Move code from CompoundConditionBuilder to ValueConditionBuilder
- Add ValueConditionBuilderTest
- Add ConditionBuilderStrategyFinderTest
Add ClassConditionBuilder
Add NamespaceConditionBuilder
Add PropertyConditionBuilder

- Add `setCompoundConditionBuilder` to the ConditionBuilder interface
to enable to use the current reference instance
Merge pull request #590 from SemanticMediaWiki/sparql-queryengine

SPARQLStore / ConditionBuilder to use strategy pattern for mapping descriptions