imgd 2.9.5

Adding a Dockerfile, updating builds and bugfixes.

Changes:

• 2.9.5:
  • Resolved issue with cache_memory introduced in 2.9.4 (hotfix)
• 2.9.4:
  • Add Dockerfile
  • Update Wercker build to use their (not anymore that) new Docker system
  • Fix log formatting re: https://github.com/op/go-logging/blob/master/CHANGELOG.md
  • Fixed a few linting issues
• 2.9.3:
  • Fix Gorilla Mux routes to use non-capturing regex groups