TMDM-8004: "Refactor MDMContextImpl to only use metadata API"

Allow use of indexes in path for getField(...) method.
Documentation (javadoc) updates.
(https://jira.talendforge.org/browse/TMDM-8004)
Upgrade to Tycho 0.22.0
Merge branch 'master' into feature/6.0/tomcat

Conflicts:
	org.talend.mdm.core.enterprise/src/com/amalto/core/history/DefaultActionFactory.java
	org.talend.mdm.core.enterprise/src/com/amalto/core/storage/services/HistoryStorage.java
	org.talend.mdm.db.migration/src/main/java/org/talend/mdm/db/migration/DBMigrationTool.java
	org.talend.mdm.workflow/src/org/talend/mdm/workflow/client/MDMContextImpl.java
	org.talend.mdm.workflow/src/org/talend/mdm/workflow/client/util/CommonUtil.java
	org.talend.mdm.workflow/test/org/talend/mdm/workflow/client/MDMContextImplTest.java
Merge branch 'master' into feature/6.0/tomcat