VFS-711 Add default constructor for StorageHelperFactory.
VFS-711 Add default constructor for StorageHelperFactory.

Conflicts:
	include/helpers/storageHelperFactory.h
	src/storageHelperFactory.cc

Former-commit-id: 229dbe2fcea1afe5f1c0ee41725943fe9c4f6db2
onedata/oneclient,onedata/helpers,onedata/oneclient,onedata/oneclient,onedata/helpers,onedata/oneclient