Sujit: For SpaceElevator Mac and Windows SHOULD NOT BE MERGED TO MASTER!!! Cuz toomany csproj changes, signing issues, and ssl issues
 - For Xamarin.Mac supporting https, had to implicitly trust everything!!
 - Now it measures transfer rate
 - File download progress is now calculated every two seconds using totalBytesWritten, FileSize instead of using chunks
 - Strong naming enabled, this requires a checkout of SpaceElevator as the certificate is in there
 - Had to disable unit-tests because the unit-test project was a "friend", and strong names does not like friends
 - All unit-tests run properly, to run unit-tests, you have to uncomment the "friend" in AssemblyInfo.cs and disable strong naming.
 - updated NuGet.exe
Note: this branch is for replacing mac-and-win-search branch
Sujit: added XAMARIN definition to Debug and Release config.
Sujit: An ugly fix for handling and gracefully failing the file download when the download url expires and/or the DownloadWorkerThread gets a NonRetryableError
Sujit: forgot to checkin csproj file after adding a file.
Sujit: All Downloader log messages have the file id in it for finding out issues..
BASE-322 #comment add 'writtenChunks' dictionary to address the case when readStack becomes inconsistent
only check for stale writing once every 5 minutes when the read stack is empty
Sujit: log msg changes
Merge branch 'feature/transfer-rate' of https://github.com/basespace/TerminalVelocity into feature/transfer-rate
Sujit: minor logging changes
Merge branch 'release/downloader-v1.0'
merge release/downloader-v1 into master.  made some methods public so unit tests can run