Remove ExtractImageDetailsDF.scala

[ruebot]

ExtractImageDetailsDF.scala came in while we were working on #223. At the time it was needed, but now it is basically redundant with ImageInformationExtractor.scala.

1. ImageInformationExtractor.scala is tied to the ImageInformationExtractor spark-submit job
2. ExtractImageDetailsDF is standalone, and is not documented anywhere other than doc comments.

The big difference between the two is ExtractImageDetailsDF includes the bytes column.

I propose we remove this now prior to the 1.0.0 release, and in the future if there is a demand for binary extract jobs, we can add them. Or just add a flag to the current jobs to include the bytes column 😉

@lintool @ianmilligan1 let me know if there is any strong disagreement with removing this.

[ianmilligan1]

This rationale makes sense to me! I'll look at the PR, and can merge unless any strong objections from @lintool.