DC classes leak memory

[shaomeng]

DCBOV leaks memory when the initialize() function called the second time and a brand new BOVCollection object is created. The old BOVCollection object is leaked.

VAPOR/lib/vdc/DCBOV.cpp

Lines 36 to 40 in 48241d0

	int DCBOV::initialize(const vector<string> &paths, const std::vector<string> &options)
	{
	_bovCollection = new BOVCollection();
	int rc = _bovCollection->Initialize(paths);

Per @sgpearse , this problem isn't limited to DCBOV class.

[sgpearse]

The DCBOV class fixes this by just checking the Collection pointer and deleting it if necessary. But the problem still exists in other DC classes (DCCF, DCMPAS, DCWRF, etc).