adjust conform to Elixir 1.9

[0xAX]

This commit provides fixing of deprecation warnings because of Elixir version 1.9.

Following changes were made:

• Mix.Releases.Logger was replaced with Conform.Logger as there is no Mix.Releases.Logger anymore.
• Mix.Dep.loaded/0 was replaced with Mix.Dep.load_on_environment/1 as the first one was deprecated and removed.
• catch/rescue order fixed.

The biggest change is in the test for creating archive with dependencies. Compliation of the fixtures projects was moved outside of Mix.Project.in_project/4 because previous behaviour was changed in the new Elixir and now it tries to build top-level (conform itself) dependencies instead of dependencies of fixture apps from conform/test directory.

Mix.task.run is replaced with direct calling of mix tasks via System.cmd/2 to avoid these issues with dependencies and now everyting works as expected.

This shouldn't break anything, because for normal Elixir project it works as expected as well.

[0xAX]

Hello @bitwalker, I saw the deprecation notice, but can you take a look at this please as we heavily use conform in our internal projects and need in Elixir 1.9 as well.

That should be no much to review as mostly warning fixes and the logic is not changed