utils: improve UploadFile function (#595)
utils: improve UploadFile function (#595)

Add / to the end of blob_path before the concatenation with filename if
the input does not end with it
GoogleCloudPlatform/compute-image-import,GoogleCloudPlatform/compute-image-import,adjackura/compute-image-tools,GoogleCloudPlatform/compute-image-tools,zmarano/compute-image-tools,adjackura/compute-image-tools,GoogleCloudPlatform/compute-daisy,GoogleCloudPlatform/compute-image-tools,GoogleCloudPlatform/compute-image-import,zmarano/compute-image-tools,adjackura/compute-image-tools,GoogleCloudPlatform/compute-image-tools,GoogleCloudPlatform/compute-daisy,zmarano/compute-image-tools