VersionChecker#missing_dependencies and #dependencies_satisfied?

Implements a few methods to perform extended upstream / downstream
cross-analysis and detection, comparing the specific requirements
in a gemfile to those in the configured build targets
Merge pull request #121 from movitto/missing_deps

VersionChecker#missing_dependencies and #dependencies_satisfied?
Pass block parameter to subsequent dependency_versions calls

Else this block will not be passed to child looks & thus will
not be invoked w/ those deps
Pass current gem version list onto Gem#versions

Fixes regression where packages were being reprocessed as they
were not being detected as already queried
Merge pull request #123 from movitto/missing-args

Missing args
Fix override of koji URL in gem_dependency_checker
Merge pull request #124 from domcleal/koji-url-override

Fix override of koji URL in gem_dependency_checker
Refactor rpm modules into smaller mixins

Minimal changes to cleanup / consolidate syntax
Split up Polisher::Gem into mixins
Split Polisher::Gemfile into mixins
Split Polisher::Git::Package into mixins
Move various modules to polisher/util directory

Extracts conf_helpers from core into its own module
More Polisher::Upstream into adaptors dir
Move Polisher::VersionChecker into adaptors, split into modules

Modules are pulled in from version_checker subdir, each
representing a target to check
Move Polisher::HasVendoredDeps into mixins dir
Move Polisher::VersionedDependencies into mixins dir
Update git modules to pull in new paths
Update rpm modules to pull in new paths

Includes small styles fixes
Move Polisher::Koji to target directory, split into modules
Move Polisher::Bodhi to targets directory