transpose array-like in herm_conj

If onsite/hopping value was supplied to the builder as array-like instead of
proper array, Hamiltonian could be generated silently without any Hermitian
conjugation, if required.

This commit fixes the problem, trying to cast the value to the proper array,
if it can't be conjugated and is not a number.

`test_builder.py::test_hermitian_conjugation` is tuned to catch the problem.

Fixes #406