Fixed IndividualFieldIterators so that operator= works
Merge pull request #216 from broadinstitute/db_iterator_patch

Fixed IndividualFieldIterator assignment operator
TestUtils: add copy/move operation test functions

Testing move and copy operations are something we do all the time and
it's not always trivial. It includes a lot of boiler plate code. These
two template functions take away the boiler plate and test the following
aspects of the copy and move operations:

* copy and move construction
* copy and move assignment
* check that self assignment doesn't destroy the object

The copy version returns all three copies made to test the functionality.

The move version returns the final moved to object. Note that the move
function will move from the parameter passed in, so that parameter
becomes unusable.

fixes #206