move deprecated functionality into an extra module

[barkhorn]

• move all deprecated implemenations (e.g. backwards compatible stuff, or support for older specs2 suites) into a separate module
• stop bundling this module with scalamock-core
• check if we can then use a linter on core in the build process, e.g.
  https://github.com/HairyFotr/linter
  https://github.com/scalastyle/scalastyle
  https://github.com/sksamuel/scapegoat

[barkhorn]

removed old specs2 MockFactory that was deprecated since 3.2

[barkhorn]

#192 made this unnessary. should exclude certain files in scapegoat instead