Support for APEL AMS (Fixes BUGZ-4016)

Reworking APEL accounting publishing to publish via ARGO AMS messaging protocol.

Summary of changes:

• thirdparty APEL SSM libs are no longer redistributed and support for STOMP is dropped
• new own code to support ARGO AMS publishing directly
  • uses client-cert authenticated HTTPS REST POST
• new default value for APEL topic to match AMS setup
• messages batch decreased to 500 to match AMS recommended size limits
• no "both" in apel_messages as instructed by APEL (either urs or summaries)

Testing:

Update ARC packages and alter APEL target config as follows:

[arex/jura/apel: KEEPOLDNAME]
# change targeturl to ARGO AMS endpoint
targeturl = https://msg.argo.grnet.gr
# delete 'topic' to rely on default
# keep same apel_messages type if you have it defined

The resulted config should look like this:

[arex/jura/apel: EGI]
targeturl = https://msg.argo.grnet.gr
gocdb_name = XX-NAME
apel_messages = summaries

What to check:

• jura.log for successful publishing
• "arcctl accounting republish" some data and check it works
• open the ticket on APEL to correlate the data and ensure that messages reaching ARGO AMS actually reaches APEL database :)