Allow specifying -v multiple times

Allow specifying -v multiple times

This commit modifies the CLI interface to allow the verbose (-v) flag to be
specified multiple times. This'll be used soon to have `-vv` indicate that more
output should be generated than `-v` during a normal build.

Currently this commit changes the behavior of whether warnings are printed to
print warnings for the **entire DAG of dependencies** if `-vv` is specified.
That is, `--cap-lints` is never passed nor is any warning from build scripts if
`-vv` is specified.