Some of the USIM-Card programming implementations do not need to look
at card responses, which means they also do not have to parse TLV
data. Lets depend on pytlv only in cases where TLV data has to be
parsed so that useser of cards that do not need at can go without
installing pytlv.
Change-Id: Ida841d74d9581e7f395751b0f74556a06a038de6