srm: refactor part of Scheduler to use guava Service

This patch takes the code that tries to keep the executors busy and
makes a Service out of it, based on AbstractExecutionThreadService.
The core logic remains unchanged, but it is collected into a
class.

The goal is to refactor the different sub-components that Scheduler
uses into Service classes and use a ServiceManager to manage their
lifecycle.

Target: master
Requires-notes: no
Requires-book: no
Patch: http://rb.dcache.org/r/6313/
Acked-by: Gerd Behrmann
webdav: log why request is rejected with permission denied

Certain configuration can lead to a user's request being rejected
inside the webdav door.  These are currently either not logged or
logged with limited information.  Either way, it is hard to
understand why a request is failing.

Target: master
Request: 2.7
Request: 2.6
Request: 2.2
Patch: http://rb.dcache.org/r/6319/
Acked-by: Gerd Behrmann
scripts: fix dcache script for Solaris machines

Patch http://rb.dcache.org/r/6293/ (committed as 19c2b522)
fixed a problem with the configuration cache not being
invalidated.

Unfortunately, in fixing a Mac-specific issue, the patch
introduced a Solaris-specific issue; specifically, that
Solaris machines do not support any options to the hostname
command.  The result is that calls like 'hostname -s' will
set the hostname to '-s'.

This patch fixes the problem by using shell's built in
filtering.

Target: master
Ticket: https://github.com/dCache/dcache/issues/335
Request: 2.7
Request: 2.6
Request: 2.2
Patch: http://rb.dcache.org/r/6315/
Acked-by: Gerd Behrmann
nfsv41: use sort timeout between door and pool manager

NFS client will backoff if it will notice that server is
not responsive. Use short timeouts to keep the pipe full.

Acked-by: Gerd Behrmann
Target: master
Require-book: no
Require-notes: no