Update filter operation to include a relation.
Refactor relationship classes
Merge branch 'future/0.1.0' of github.com:Stratio/stratio-meta into future/0.1.0

Conflicts:
	meta-core/src/main/java/com/stratio/meta2/core/statements/DeleteStatement.java
Working on grammar refactor for select statements.
Merge branch 'future/0.1.0' of github.com:Stratio/stratio-meta into future/0.1.0

Conflicts:
	meta-core/src/main/java/com/stratio/meta/core/grammar/Meta.g
	meta-core/src/main/java/com/stratio/meta2/core/statements/SelectStatement.java