Add missing constructor arg to Processor in tests

Hey! Thanks for making `asciidoc-bib`! Being able to use .bib citations in an AsciiDoc is quite useful.

I started trying to use `asciidoc-bib` and had some problems, and when I tried to run the test suite I noticed some failures. It seems to just simply be that an additional argument to the `Processor` constructor was added but not in the tests. 

The lines added to the `bin/` executables are so that when one runs the executables directly they attempt to use the current source instead of the gem installed on the system. When I was trying to work on the code I was initially confused because I wasn't seeing my modifications reflected when running one of the scripts. I feel this makes contributing more straightforward but I leave it up to your discretion. (For reference, the lines were shamelessly borrowed from [brakeman](https://github.com/presidentbeef/brakeman/blob/master/bin/brakeman).)

I have created an issue for the bug I encountered when trying to use `asciidoctor-bib`.