that results in missing tail bits when the master is heavily loaded.

Added autocompletion to build after other textbox, and textboxes can now use autocompletion without needing a true field via the autoCompleteField attribute.

- Pass TaskListener to enable listeners to report what they are doing
- Added another callback to report a failure

I wasn't initially planning to do this, but it turns out more people needed this feature than I thought.

I left the text as is, but defined a mechanism to override this in the plugin, in a possibly context sensitive way. For example, a plugin can replace this text on a job-by-job basis, or by looking at some property/builder/etc.

While the original report is in https://cloudbees.zendesk.com/tickets/427, this fix also takes care of JENKINS-4220.

[FIXED JENKINS-8917] Plugin Manager incorrectly displays "Changes will take effect when you restart Jenkins".

the master.

Set M2_Home for maven builds and add maven to the path so if the build
needs to run maven from maven (or maven from ant from maven) it can.

Otherwise plugin classes won't resolve.

Ant build step had quite a mix: buildFile and antOpts expanded against
env, properties against buildVariables, and targets against both.
Now merging buildVariables into env and applying to all.

 I added a mode where one can launch a child process without the built-in pumping support, making it trivial to read until EOF in the distributed environments.

 This concludes the fix.