v1.0.0: Remove unused XenAPI call and add cleanup documentation

• Document motivation for complex runtime cleanup code
• Mention that systemd service appears to be failed when stopped
• Remove unused variable and VDI.get_record XenAPI call

v0.5.0: Limit simultaneous connections to a maximum of 16

Merge pull request #26 from thomassa/limit-connections

CP-24917: limit simultaneous connections

v0.4.0

• Update dependencies to work with xen-api-client 0.11.0
• CP-25017: Ask xapi whether to use TLS or NOTLS
• CA-267340: Attach VBD & serve VDI as read-only

v0.3.0: Use XenAPI instead of SMAPIv2, clean up leaked VBDs

• Do VBD.plug to dom0 using XenAPI calls instead of interacting with SMAPIv2
• Make sure we clean up the VBDs we create & plug to dom0:
  • Clean up VBDs on SIGTERM (& SIGINT)
  • Persistently store the list of VBDs that we have to clean up, and clean up any leaked ones at startup
  • Wait for xapi to be up before trying to log in to do the cleanups
• Improved logging
• Test Vbd_store module used to persistently track VBDs we create using alcotest
• Compatibility update for xen-api-client v0.10.0

v0.2.0: TLS support and improved logging

• Use Lwt_log for logging
• Preliminary TLS functionality

Initial release

Merge pull request #12 from gaborigloi/CA-264333

CA-264333: use local Unix domain socket and remove username & password authenticion