Bug 1074632 - RFE: Manage storage node snapshots

2nd piece of impl above BZ. This patch adds server side capability to manage
snapshots for storage cluster. This basically means that we regularly run
takeSnaphost operation with several parameters - so user can decide whether
to keep all of them, keep last or move older ones to specified location.

6 new private/readonly system settings have been introduced - those settings
can be updated only via Storage admin pages.

User can enable/disable snapshots management of storage cluster and set cron
expression to run management task regulary (additional 4 settings are
basically parameters for takeSnapshot operation introduced within previous
commit for this BZ). When Cluster Setting is saved in UI we re-schedule
takeSnapshot operations on all StorageNode resources in inventory.

Snapshot related code was removed from
StorageNodeManagerBean#runClusterMaintenance()
Bug 1041393 - alert notification of type Resource operations is not
correctly rendered by API

AlertNotificationRest extended with extraConfig field where we now output
notification extra config (in case of Resource Operations alert sender, it's
input parameters for operation)

With this commit we now also properly render alert notification config
(simple property types mapped correctly to JSON/XML, not "just" string
values)

This commit fixes ConfigurationHelper#configurationToMap which transforms
Configuration to generic Map, now it can work without Configuration
Definition
- as a fall-back it maps all simple properties to string values.
[BZ 1083479] - Second invocation of about dialog fails - creating the dialog from scratch (instead of using the cached instance that was causing the issue). Also adding a link to GitHub commit corresponding to the build number (only for RHQ).
Bug 1127264 - Creating alert notification of type Resource Operations
ignores extraConfig field
[1126853] Alert does not trigger if defined with 'disable when fired'
This was undetected fallout from the work done in BZ 1110434.  Although,
it's fallout that doesn't make a lot of sense.  It's either a bug in
HornetQ/Arjuna/EAP interaction Tx management, or we violated some very
subtle J2EE/JTA rule.  Basically this is what was happening:
1) alert condition consumer onMessage is invoked (with default CMT Tx semantics)
2) it invokes a series of nested SLSB calls with various Tx semantics, including
   REQUIRED, REQUIRES_NEW and NOT_SUPPORTED.
3) The NOT_SUPPORTED method hangs on method return, as such some downstream
   processing commits (due to REQUIRES_NEW semantics) but the upstream calls
   don't complete.  So even though the alerting all worked, it never got
   to commit.
4) After 10 minutes the Tx reaper comes along and cancels the hanging Tx.

The fix/workaround is actually easy. Instead of calling the general purpose
disableAlertDefinitions() method (which supports mass-disable and therefore
uses the NOT_SUPPORTED semantics to help chunk transactioning) we switch to
the disableResourceAlertDefinitions() method (which uses REQUIRED) because
we know we are dealing with a single resource-level alert definition.
We make an analogous change for enable.  We are basically avoiding the
issue.
Bug 1070323 - (JON3-41) JBoss ON must support JBoss Diagnostic Reporter
(JDR)

Increase JDR request timeout to 10minutes
Bug 1119240 - Adding http-interface in the host controller's host-slave.xml
is not recognised by JBoss ON Agent causing Host Controller's availability
to stay DOWN

throw InvalidPluginConfiguration exception when http mgmt interface port is
detected as 0 (not-detected). User is advised to set his host controller up
and then update connection settings.
Merge pull request #97 from lzoubek/bugs/1074632

Bug 1074632 - RFE: Manage storage node snapshots (part. 2)