Fix several issues in recent alarms changes

The patch fixes several issues introduced in ff5e0423492a4931b188e48e2599962f1013a377:

- dcache-common imports hikaricp, which means that several components that
  don't make use of databases now pull in database related code (like the srm client).

- Missing @Override annotations in AlarmEnabledDataSource

- Redundant shutdown method in AlarmEnabledDataSource (use close)

- Infinite loop in uncaught exception handler (on IOException that isn't an
  out of file descriptor error, the code would loop forever)

- Complex code before kill on fatal JVM error (which in case of OOM may lead to
  another OOM rather than a shutdown)

To fix the HikariCP dependency I had to update to HikariCP 2.0.1.

Target: trunk
Require-notes: no
Require-book: no
Acked-by: Albert Rossi <arossi@fnal.gov>
Patch: https://rb.dcache.org/r/7188/
cells: Fix deadlock during startup

The patch fixes a regression introduced in 2.8. The regression may cause a
deadlock in cells if they receive a message during startup.  This may happen
when restarting individual services in a busy dCache. It is unlikely to happen
when "cold starting" dCache.

The problem is caused by AbstractCell running most cell initialization on the
cell message thread (to ensure the correct context is used). If a message is
received before this task is created, the message will block the message thread
waiting for the cell startup to complete, however the cell startup cannot
complete because the initialization task cannot be executed due to the message
thread being blocked.

The patch solves this by returning a NoRouteToCellException when receiving a
message before cell startup has completed. Thus the blocking behaviour is
removed and the deadlock is avoided.

An unused shutdown gate is removed too.

Target: trunk
Require-notes: yes
Require-book: no
Request: 2.10
Request: 2.9
Request: 2.8
Acked-by: Paul Millar <paul.millar@desy.de>
Patch: https://rb.dcache.org/r/7187/
Clean up Spring instantiation of database connection pools

Target: trunk
Require-notes: no
Require-book: no
Acked-by: Paul Millar <paul.millar@desy.de>
Patch: https://rb.dcache.org/r/7189/
Merge branch 'master' into development/cdmi1
Clean-up & Merge.