Add Omnibus::Project#dependency DSL method

This cleans up the DSL a bit by allowing the specification of
build-time dependencies one-at-a-time.
Edit project template to reflect DSL changes
Make MissingProjectConfiguration errors work
Add a project validation step

This should fail the build early if required information has not been
set.  Otherwise all the software dependencies will get built first.
add Omnibus::Software#dependency DSL method

This cleans up the DSL a bit by allowing the specification of
dependencies one-at-a-time.
ignore `--path` global option on appropriate commands

Having unused CLI options is just confusing to the end user!