PBXVariantGroups treated as PBXGroups.
Merge pull request #18 from stefanceriu/master

PBXVariantGroups
fixes XCTargets members array by resolving PBXBuildFile to PBXFileRefs instead of PBXFileRefs to PBXBuildFile
treats PBXReferenceProxys equal to PBXFileReferences. This solves problems with libs included from target dependencies.
Merge pull request #19 from iosphere/master

fixes problems with XCTarget's members array
Update README.md
Fix failing test.
Code formatting.
Clean up.
Make adding a group spec pass again.
Fix delete group in GroupSpec
comment out in-progress spec.
Convert tests to plain OCUnit. Better IDE integration.
Convert tests to plain OCUnit.
Remove Kiwi
Clean up build.
Update build config props.
Add appledoc path for jenkins.
Fix file encoding key.
Update README.md