Support different names for opj_decompress

[adam-vessey]

The configuration does not presently allow the full path to the executable to be specified--only the path of the directory where we expect opj_decompress to be located; however, some distros such as CentOS (and RedHat) name their executables (from their openjpeg2-tools packages) starting with opj2_... so opj2_decompress and the like...

... it's possible to create symlinks to workaround, but seems like we could also just allow the specification of the full path of the executable... or possibly add the ability to specify the name of the executable in addition to the path?

... thoughts?

[adolski]

I think a symlink is the way to go for now given the resource constraints on this project. In the longer term I would like to call into the OpenJPEG library and not have to deal with opj_decompress.