Require the common dependencies once

Motivation: there was missing

    require 'katello_api'

in `provider.rb`. Depending on the order the files were loaded in
the hammer_cli_katello.rb, it caused:

    uninitialized constant KatelloApi::Resources
refs #4119 - hammer-manifest - new subscription manifest upload command

refs #4119 - hammer-manifest - removed commented code
Remove unused file
Merge pull request #24 from iNecas/eliminate-requires

Require the common dependencies once
Merge pull request #25 from thomasmckay/hammer-manifest

refs #4119 - hammer-manifest - new subscription manifest upload command