Fixes #336 Assertion Failed : _asyncTaskCount >= 0
Fixes #336 Assertion Failed : _asyncTaskCount >= 0

The issue is that the result of the onCompletion block of the
CBLMultipartUploader could be null when there was an error occurred.
Hence passing the result object of the block to the removeRemoteRequest
method is not correct and will result to an error that the finished
uploader will not be removed from the remote request array.

When the app is suspended in the background, the replication (pusher)
will stop all of the requests that are in the remote request array.
Calling stop on the finished uploader will cause the onCompletion block
to be called again and will lead to the ‘Assertion Failed :
_asyncTaskCount >= 0’ error when asyncTasksFinished: method is invoked
inside the onCompletion block.

The fix is to use the original uploader object to pass to
removeRemoteRequest method instead of using the result object from the
onCompletion block.

mz2/couchbase-lite-ios,lordkev/couchbase-lite-ios,mz2/couchbase-lite-ios,gotmyjobs/couchbase-lite-ios,gotmyjobs/couchbase-lite-ios,Chavenay/couchbase-lite-ios,gotmyjobs/couchbase-lite-ios,mz2/couchbase-lite-ios,macoscope/couchbase-lite-ios,amco/couchbase-lite-ios,couchbase/couchbase-lite-ios,couchbase/couchbase-lite-ios,amco/couchbase-lite-ios,amco/couchbase-lite-ios,tomco/couchbase-lite-ios,ipmobiletech/couchbase-lite-ios,tomco/couchbase-lite-ios,ryuzmukhametov/couchbase-lite-ios,lordkev/couchbase-lite-ios,pellekrogholt/couchbase-lite-ios,pegli/couchbase-lite-ios,pellekrogholt/couchbase-lite-ios,couchbase/couchbase-lite-ios,amco/couchbase-lite-ios,macoscope/couchbase-lite-ios,macoscope/couchbase-lite-ios,pegli/couchbase-lite-ios,brendand/couchbase-lite-ios,brendand/couchbase-lite-ios,brendand/couchbase-lite-ios,lordkev/couchbase-lite-ios,tomco/couchbase-lite-ios,pellekrogholt/couchbase-lite-ios,ryuzmukhametov/couchbase-lite-ios,ryuzmukhametov/couchbase-lite-ios,pellekrogholt/couchbase-lite-ios,macoscope/couchbase-lite-ios,Chavenay/couchbase-lite-ios,ipmobiletech/couchbase-lite-ios,alfared/couchbase-lite-ios,ipmobiletech/couchbase-lite-ios,amco/couchbase-lite-ios,ryuzmukhametov/couchbase-lite-ios,couchbase/couchbase-lite-ios,alfared/couchbase-lite-ios,gotmyjobs/couchbase-lite-ios,couchbase/couchbase-lite-ios,amco/couchbase-lite-ios,amco/couchbase-lite-ios,alfared/couchbase-lite-ios,lordkev/couchbase-lite-ios,tomco/couchbase-lite-ios,ipmobiletech/couchbase-lite-ios,alfared/couchbase-lite-ios,pegli/couchbase-lite-ios,couchbase/couchbase-lite-ios,brendand/couchbase-lite-ios,Chavenay/couchbase-lite-ios,pegli/couchbase-lite-ios,brendand/couchbase-lite-ios