Review and apply comments for remaining initial commits

[lforchini-ntnx]

The remaining initial commits have very few comments, so I've condensed them here:

• add a journald-aware log style #15 Mention JSON format in README
• add tool to parse logs #16 Consider structured logging
• add a fleet snapshot D-Bus method #17 SnapshotVm use serde(flatten) to allow for struct re-use
• add dedicated D-Bus version method #30 Version env var set by cargo.toml + build.rs? or env!("CARGO_PKG_VERSION"). Source mentions a build.rs so maybe not included in that commit?