upload: adding --ignore-lsc CLI options

.gz images are decompressed locally before uploading them.
gzip doesn't provide accurate informations about the real
uncompressed file size and so the free space on local tmp dir
are checked against the maximum image size. This, with
thin disk images (sparse files), is often too conservative.
Adding a CLI option to ignore this kind of
errors.

Adding support for sparse file in the NFS copy

Change-Id: I8ae3e90c4abd832891088899e713c26eac495a4d
Bug-Url: https://bugzilla.redhat.com/1119798
Signed-off-by: Simone Tiraboschi <stirabos@redhat.com>