CLOUDSTACK-7528: More verbose logging when sending alert fails

When sendAlert is called on an AlertManager impl, if it fails it logs that
something was wrong but does not log the body of the issue/error. This means
we tell the user/admin that there was an issue but don't share the "issue"
with them at all as the email alert fail (or that they were not initialized).

(cherry picked from commit 91fd8d7cd5d5a83bf75f5f2972ad2eb2a4a07694)
Signed-off-by: Rohit Yadav <rohit.yadav@shapeblue.com>

Conflicts:
	server/src/com/cloud/alert/AlertManagerImpl.java
appliance: fix newer debian iso links and checksums for debian

Signed-off-by: Rohit Yadav <rohit.yadav@shapeblue.com>
(cherry picked from commit ac5309b8b47ddb1e5588a2d5090f2bcce0e7c2a4)

Conflicts:
	tools/appliance/definitions/systemvm64template/definition.rb
	tools/appliance/definitions/systemvmtemplate/definition.rb
CLOUDSTACK-6099 live migration is failing for vm deployed using dynaic compute offerings with NPE

Signed-off-by: Rohit Yadav <rohit.yadav@shapeblue.com>
Merge remote-tracking branch 'origin/hotfix/4.4/CLOUDSTACK-6099' into 4.4