Initial (inadequate) attempt to fix volume number formatting.

Addresses Trac #63. Added test cases, and got volume number in the
right place when it regards the container (e.g. book section,
encyclopedia article). However, it is not yet in the right place for
citations that don't have a container (e.g. book).
Corrected vol. no. placement for books. Vol. no. now correct in all cases

Fixes Trac #63.