[Command] Remove deprecated pod push
Merge pull request #2469 from CocoaPods/fabio/remove-pod-push

[Command] Remove deprecated pod push
[gemspec] Bump xcodeproj to 0.19.3

Fixes #2631.
[Gemspec] Require Resolver
[Resolver] Start using the resolver gem!
[Resolver] Add rudimentary lockfile handling, equivalent to the old behavior
[ResolverSpec] Disable spec that really belongs in the Analyzer
[Resolver] Restore support for HEAD pods
[Resolver] Return lazy specifications in Set#all_specifications
[Resolver] Allow LazySpecs to stay unrealized for longer
[Resolver] Sort dependencies by number of possibilities, improving performance exponentially on large Podfiles
[Resolver] Verify platform compatability
[Resolver] Move vertex method into Resolver gem
[Specs] Update to match update in master repo submodule
[Resolver] Only make the ResolverError include InformativeError inside a command
[Resolver] Delete dead code