[BZ 1022943] Ability to trigger update of plugins on agents from UI and API
This is stage 1 of the series of commits to enable more user-friendly
handling of plugin updates.

It provides basic support for triggering updates of plugins on agents
by calling server-side APIs/GUI.
Merge remote-tracking branch 'origin/master' into bug/1022943

Conflicts:
	modules/enterprise/server/itests-2/src/test/java/org/rhq/enterprise/server/test/TestAgentClient.java
	modules/enterprise/server/jar/src/main/java/org/rhq/enterprise/server/agentclient/AgentClient.java
[BZ 1022943] Added ability to check status of plugin update on agents
Merge remote-tracking branch 'origin/master' into bug/1022943

This is to have the fix for BZ 1076389 (which blocks BZ 1022943) in this branch.
[BZ 1022943] Fixes to PluginCriteria
[BZ 1022943] Reporting changes of plugin deployments
note in the javadoc that the deploy* methods are synchronous.
[BZ 1022943] Added a new REST endpoint for working with agent plugins.
First cut of a Aerogear-Unified-Push-Server alert plugin.
1061311 - rhqctl contains user modifiable values that result in an unsupported rhqctl script
- Fix issues with rhq-encode-password.sh|bat
- Don't abort a script if rhq-server-env.sh|bat is not found
BZ 1090829 - see if the port is already in use.
If the port is in use, not only will this abort if another agent was
installed, but it will abort if anything has taken the port the agent
wants to use.
[BZ 1075875] remote API client version is 'undefined' when client is
packaged as executable JAR

if rhq-client.version-check=false - do not even try to detect the version
and log any message - this is exactly what this property says : "NO version
check, please"

introduced 'rhq.client.version' system property, that you can set or pass to
your client that would take precedence over what could be found in manifest
(if it exists).
BZ 1090453 - internal api change
BZ 1091409 - right now, we don't support custom env files. To prohibit people from setting one, all setters and fields are private. If we support this in the future, we set these back to public and there are a couple places in the GUI code where we need to uncomment some lines that set the env file.
[BZ 1089108] File Systems -> Free Space graph off by a factor of 1000. Refactored to a much cleaner solution with no IF logic. Removed some dead code from Measurement helper classes.
[665508] rhq:url-archive, rhq:archive should support destinationFile/destinationDir
Add "destinationDir" attribute for the archive targets.  Note that it can only
be used in conjunction with "exploded=false".
BZ 1091015 - be able to delete agent even if it doesn't exist on the file system
BZ 1091339 - validate the port field properly
Bump ems version to 1.3.5-rhq for lighter connection checking.
BZ 1090476 - do not check for status if the agent wasn't found. this makes the UI more responsive. There is no need to check status anyway since we don't know where the agent is
BZ 1090448 - make the remote agent install UI more pretty