Solve issue 459

[Christovis]

This PR addresses issue #459 .

Implements the following:

• Catching connection error which is raised due to Max retries exceeded
• solving it by waiting 30 sec before resuming

Tested on the following 3GPP mailing lists:

3GPP_TSG_GERAN_WG1: 100%|########################################| 1643/1643 [55:17<00:00,  2.02s/it]
3GPP_TSG_GERAN_WG2: 100%|########################################| 2457/2457 [1:22:02<00:00,  2.00s/it]
3GPP_TSG_RAN_WG4_CA: 100%|#######################################| 1654/1654 [49:56<00:00,  1.81s/it]

read as: (3GPP list name): 100%|####################| (total nr. of messages)/ [(total time needed)<00:00, (ave. time per message)]