update Dockerfile to follow conventions

change instructions to be uppercase
change ADD to COPY
change cmd exec docker-registry to CMD ["docker-registry"]
Merge pull request #620 from unclejack/dockerfile_changes

update Dockerfile to follow conventions
fix forgotten lowercase cmd
Merge pull request #621 from unclejack/uppercase_cmd

fix forgotten lowercase cmd
Config template: add boto_calling_format S3 option

Using the "ordinary" calling format can be useful when using
a bucket whose name contains periods (otherwise the AWS SSL
certificate may be refused because it is several subdomains
deep).
Merge pull request #625 from krallin/aws-calling-format

Config template: add boto_calling_format S3 option
Correcting typos in the {ADVANCED, CONTRIBUTING, README}.md files.
Merge pull request #628 from krook/fix-markdown-typoes

Correcting typos in the {ADVANCED, CONTRIBUTING, README}.md files.