Particle table - Critique & Suggestions welcome.

At this stage, I am still committing to this pull request, so please don't merge until it is deemed ready, I am putting this 'out there' I would like suggestions & criticisms from the community. 

First attempt at a particle table that meets the current requirements on ongoing projects. The concept is to create a list of particle type/names that will be later utilised by the tally class. The idea being that, for tallies at least one could create a new tally, 

    tally = tally("flux","photon".....) 
or
    tally = tally("flux","anti-electron-neutrino".....) 

The tally class would then lookup this particle name and then insert the PyNE particle name into the tally. This would then later be understood by MC code specific write functions or throw errors if not present.