Added proper .gitignore
Added general improvements (see desc)

* Remove class methods initWithDelegate: (used instance ones).
* Remove initWithDelegate: methods from subclasses of BRRequest (just BRRequest has the initWithDelegate: method)
* Code conventions.
Fixed shouldOverwriteFileWithRequest: method never called (https://github.com/lloydsargent/BlackRaccoon/issues/12)
Fixed warnings
Added fullRemotePath to BRRequestDownload and BRRequestUpload
Added uuid property to BRRequest
Added passive mode