Detail Docker usage

• Document Docker steps.
• Simplify Docker hooks.
• Expose additional build arguments.

Code cleanup

• Update bash scripts.
• Tidy-up Markdown.
• Fix SVG compatibility issues.
• Add support for Code Climate.

v0.5.1

Remove legacy references to resin

Initial release

• Working balena Dockerfile template for ARM.
• Working traditional Dockerfiles for ARM and x86.
• Documentation.
• Uses Flic SDK for Linux v0.5.