LMS-1811 Refactoring DssClient to an AbstractClient.

...temsx/cisd/openbis/dss/client/api/cli/AbstractClient.java

...emsx/cisd/openbis/dss/client/api/cli/AbstractCommand.java

...sd/openbis/dss/client/api/cli/AbstractCommandFactory.java

...d/openbis/dss/client/api/cli/AbstractDataSetExecutor.java

...x/cisd/openbis/dss/client/api/cli/AbstractDssCommand.java

...msx/cisd/openbis/dss/client/api/cli/AbstractExecutor.java

...temsx/cisd/openbis/dss/client/api/cli/CommandFactory.java

.../systemsx/cisd/openbis/dss/client/api/cli/CommandGet.java

...systemsx/cisd/openbis/dss/client/api/cli/CommandHelp.java

...h/systemsx/cisd/openbis/dss/client/api/cli/CommandLs.java

.../systemsx/cisd/openbis/dss/client/api/cli/CommandPut.java

...h/systemsx/cisd/openbis/dss/client/api/cli/DssClient.java

...emsx/cisd/openbis/dss/client/api/cli/ICommandFactory.java

...temsx/cisd/openbis/dss/client/api/cli/CommandGetTest.java

...stemsx/cisd/openbis/dss/client/api/cli/CommandLsTest.java

...temsx/cisd/openbis/dss/client/api/cli/CommandPutTest.java