search specfile; optionally ignore email addresses; handle directories on el7

This commit makes the following changes:

* Searches files in the SPECS folder (i.e. the specfile) in addition to SOURCES
* Adds a command line option '--ignore-email' to filter text that matches the
  pattern '<email@redhat.com>'. Text in this pattern occurs commonly in
  changelogs (e.g. in the specfile) and is not usually a branding issue.
* Fixes a bug on el7 that was reporting directores as binary files.
* Removes the '-w' option for specifying the working-dir. It can still
  be specified using '--working-dir', and removing it makes help output
  easier to read.
* Remove an unused/commented-out command-line option