This permits custom attributes to be passed to the bibliography list
such as `reversed` or `start` to permit custom numbering.

See inukshuk#148

See #147

See #147

{} could be matched arbitrarily inside of a {} pattern, in addition to
the expected behaviour of nested pairs. (oops)

Closes #143

See #139

test-unit dependency for cucumber should be specified as >= 2.2

Also add Ruby 2.3.0 to the Travis CI configuration.

Make bibtex converter use configured filters.

The bibtex converter class was not making use of the `bibtex_filters`
global configuration option.

Add filter for \superscript LaTeX command

This filter converts \textsuperscript latex formatting into <sup> html
tags. It should be used before the `latex` filter to prevent premature
stripping of {} groups.

Also adds superscript to the default filters and documents the
bibtex_filters parameter in README.md

References inukshuk/jekyll-scholar#132

Details page page.title variable should use LaTeX filtered entry

See #129

See #129

Export authors into an array under entry.author_array

This permits easier iteration over an arbitrary number of authors.

See #127

See #127

Added --group_by option for bibliography tag