Complete Pkg.Resolve modularity + fixes

fixes:
1) fix check_repository (also add julia_version argument)
2) fix pkgs/vers/deps gathering and filtering
fix #3196
add convert(::Type{Rational}, ::Integer). closes #3202
Small updates to the mac app bundle.
fix #3191 (remove ui)
ui symlink is no longer installed in make dist.
Fix dump of types without .names (former BitsKinds)
Fix Pkg.Resolve.sanity_check

Test was failing to properly check in case of
dependency graphs with tight cycles.
Add Pkg.Resolve tests