Changed CloudFileUploadTimeoutAsync to use PORTABLE conditional compilation consistently with ASPNET_K
Changed FileReadStreamSeekTestAsync to use matching data types in asserts.
Changed FileWriteStreamFlushTestAsync to use PORTABLE conditional compilation consistently with ASPNET_K.
Change TestHelper.ExpectedException method to use PORTABLE condition consistently with ASPNET_K to fix DisableContentMD5ValidationTestAsync and FileDisableContentMD5ValidationTestAsync.