For some mysterious reason, not all COMMON_MESSAGEs get sent to
modem. This patch adds a retry counter that tries to make sure an
answer is always received.
This patch adds an API for querying the ISI version of the resource
with which the client is associated. This information is only
available after g_isi_verify() has been called on the client. This is
because we use the version query message as a vehicle for reachability
checking.