Consistency pass for Block Storage samples.

To make it less jarring when you flip between the languages used for code samples, I'm trawling through and touching up any inconsistencies I find, such as:

 * Indentation levels.
 * Comment verbiage.
 * Variable names.
 * Placeholder syntax: `{camelCase}` and enclosed in quotes where necessary.
 * Prefer valid placeholder *values* to `{placeholder}` constructs.