Add --no-config option

[msabramo]

This lets us get rid of YAML configuration file couldn't be found at /no/config. Using defaults. warnings; especially when running the unit tests.

$ bundle exec rake test
/usr/local/Cellar/ruby/2.3.1/bin/ruby -I"lib:lib:test" -I"/Users/marca/dev/git-repos/aptly_cli/.bundle/gems/gems/rake-10.5.0/lib" "/Users/marca/dev/git-repos/aptly_cli/.bundle/gems/gems/rake-10.5.0/lib/rake/rake_test_loader.rb" "test/test_aptly_cli_configure.rb" "test/test_aptly_command.rb" "test/test_aptly_file.rb" "test/test_aptly_misc.rb" "test/test_aptly_package.rb" "test/test_aptly_publish.rb" "test/test_aptly_repo.rb" "test/test_aptly_snapshot.rb"
/Users/marca/dev/git-repos/aptly_cli/test/minitest_helper.rb:4:in `<top (required)>': [DEPRECATION] ::[] is deprecated. Use ::new instead.
Run options: --seed 26736

.................................................................

Finished in 0.460966s, 141.0082 runs/s, 232.1212 assertions/s.

65 runs, 107 assertions, 0 failures, 0 errors, 0 skips
Coverage report generated for Unit Tests to /Users/marca/dev/git-repos/aptly_cli/coverage. 636 / 658 LOC (96.66%) covered.
[Coveralls] Outside the CI environment, not sending data.

[coveralls]

Coverage increased (+0.008%) to 97.222% when pulling 5b93f20 on msabramo:no-config into e0b3638 on sepulworld:master.

[sepulworld]

Thank you! Much cleaner output 💯