Include middle name in bibtex output, format initials

[lfoppiano]

This PR fixes the issue reported in #1351:

• adds the middle name if present, do not add comma between first and middle name
• add period if first or middle name are initials

Now the output should be correct:

curl -X POST "http://localhost:8070/api/processCitation" \
  -H "Accept: application/x-bibtex" \
  --data-urlencode "citations=Dill, K. A., Ozkan, S. B., Shell, M. S. & Weikl, T. R. The protein folding problem. Annu. Rev. Biophys. 37, 289–316 (2008)."

@article{-1,
  author = {Dill, K. A. and Ozkan, S. B. and Shell, M. S. and Weikl, T. R.},
  title = {The protein folding problem},
  journal = {Annu. Rev. Biophys},
  date = {2008},
  year = {2008},
  pages = {289--316},
  volume = {37}
}