Validate application name of package

[tsloughter]

I think we should be validating that the compiled application for a hex package is the same as the name of the dependency given in deps.

Meaning {deps, [erl_pipeline]} should error with a message about the user should be using {deps, [{pipeline, {pkg, erl_pipeline}}]}.

As I write that I remember I hate error messages where the program clearly knows what you meant and should just do it... hm. So I guess I have to be positive that there is a need for the dep and app name to match and to not just get it from the .app file?

Either way, a change is needed to address the case of building a release failing when the config is like:

{deps, [erl_pipeline]}.

{relx, [{release, {pipe_rel, "0.1.0"},
         [pipelinel]},

===> Application needed for release not found: pipeline

Originally reported here: https://github.com/erlware/relx/issues/892