H(curl) elements

[jacobmerson]

PCMS will need to support NIMROD field definitions SCOREC/pcms#241

NIMROD uses H(Curl) finite elements spaces. we will need to have support for the appropriate Nedelec element. It looks like this is already implemented in core, so hopefully it won't be too bad to implement. https://github.com/SCOREC/core/blob/83dfbb2175bc9434f20959fc11b72a785e046c3d/apf/apfNedelec.cc#L516