Add task to get the release name and vsn

[KoFish]

Due to the complexity in calculating the release name relx should have a task that simply prints what name and version relx will use when building a new release. This is especially useful for the use of semver in combination with tools like erlang.mk.

My suggested interaction would be something like:

$ cat config.relx
{release, {some_project_release, semver}, ...}
$ ./relx release-name
some_project_release 1.2.3+build.4.ref543210

[stchar]

+1

[lrascao]

@stchar @KoFish would any of you be available to propose a PR to add this functionality

[stchar]

Hi, @Irascao,

Unfortenatly, I'm lityle bit busy for now, however i can try to make it 2-3 weeks.

[lrascao]

cool, thanks!