Is there any way via any API to track Metadata history?

Starting with Winter'16 the SetupAuditTrail object has now been exposed via the Salesforce API's and within Apex via SOQL. Its pretty much a mirror of the CSV download, accept for the Delegate User (though since this is documented, this could be a bug or something i'm missing). The following is a sample query from my latest blog where i dig into it a little further...

List<SetupAuditTrail> stuffDoneByConsultants = 
    [SELECT Id,
     FROM SetupAuditTrail 
     WHERE CreatedBy.Email LIKE ''];

I think you're looking for the Setup Audit Trail. This setup screen should display the last 20 metadata modifications, the last 6 months can be downloaded as csv.

Setup > Security Controls > View Setup Audit Trail

View Setup Audit Trail

Update: Apparently this data is not exposed/supported by the Metadata API (or any other). There is an idea on the IdeaExchange on which you can vote: Make Audit Setup Trail History available via the API