Ignore .git entries when getting path's hash
Refactored out find_cache()

Created find_cache() which calculates the cache for the given
parameters.
Added special handling for WORKDIR

Create a Dockerfile just for WORKDIR entries and then check them against
the buildcache.
Merge branch 'workdir_cache'
Tag the image with the final name at the end
Merge branch 'tag_at_end'
Set option --no-cache to match docker build
Merge branch 'no_cache_option'