Update readme for consistency

[jondkelley]

Making slight modifications for better consistency across the doc

• Removing quotes from readme. Quotes in cases like docker-compose are provided as literals and invalidate the config. Quotes are also only necessary in YaML if it will create type-aware objects such as integers or arrays.
• Removing quotes from bash commands as they're not really required unless the value has spaces.
• Removing single quotes from image name, not necessary.

[tanberry]

Thanks @jondkelley I am really not sure why those quotation marks were ever even there, single or double.