Disable removal of CID packet from cache

For some reason, we were removing a valid CID packet from cache after it
was delivered to the application. However, the corresponding map that
held the status of the packet was not updated. Causing click transport
XreadChunk() code to believe that the CID is available when it was
requested for a second time during the same file transfer in xftp.
This change could possibly cause a memory leak. If it does we will have
to find the underlying logic for why the CID was being dropped from
memory and how the corresponding map should be updated to reflect that.
Fix re-requesting of chunk list

In case of network disruption, the xftp client re-requests chunk list
from the server. The couter to do that was not being incremented between
iterations of the main loop, so the re-requesting was not happening.
Fixed by simply moving counter out of the if statement.
Xftp server now uses crypto SID and rendezvous