added Index::commitToRepository method that creates a new commit out of the index within the parent repository
added new class CommitOperation
fixed funny typo in GitWrap object creation
removed obsolete method Index::commitToRepository()
added method Signature::defaultSignature()
added static helper method Commit::commitList2git()
added static method Commit::create() -> creates a new commit and adds it to a repository
added commit operation

This is WIP and meant as a discussion basis.
added export declarations and virtual dtor to BaseOperationProvider
added setters/getters for plain information data
changed commit operation providers to QSharedData
added asserts when modifying running operations
minor change: return type should use defined type
moved members to pimpl class
create a commit from a list of parent oid's
moved base class OperationBaseProvider to BaseOperations header

further united provider classes to one CommitOperationProvider class
implemented the commit operation's run method
added Git::Index::commitOperation() (unfinished)
fixed little typo
private implementation of IndexCommitOperationProvider