Auto merge of #1507 - jimmycuadra:cargo-new-semver, r=alexcrichton

This patch updates the initial version of packages generated with `cargo new` to 0.1.0 (rather than 0.0.1), which better follows SemVer. The docs are also updated to show examples that follow this convention.

For reference, the same change was recently made in Bundler for the Ruby ecosystem: bundler/bundler#3322