WIP: retrieve simple entity

CMakeLists.txt

include/caosdb/authentication.h

include/caosdb/connection.h

include/caosdb/entity.h

include/caosdb/info.h

include/caosdb/transaction.h

src/CMakeLists.txt

src/caosdb/entity.cpp

src/caosdb/info.cpp

src/caosdb/transaction.cpp

src/caosdbcli.cpp

test/test_connection.cpp

test/test_info.cpp

test/test_transaction.cpp