This is done by introducing a new base type 'BuildDiscarder' that's
extensible. Plugins can implement their own logics.

This reverts commit e2168722.

Fixed the HTTP request thread saturation problem with Winstone.

eval("") is no-op in IE but window.execScript("") isn't.
So bring the uniformity outside

This was lost in 0f2737f8

While several plugins implemented the interface under the old name, only core was checkcasting it.

At this time the target project is unset so it has no known type and we just have to assume the threshold is valid.

First, display instructions when the user has CONNECT, not necessarily ADMINISTER.
Second, when anonymous users cannot CONNECT, show how to use -jnlpCredentials
(and do not bother showing javaws, since it does not work in this case).

[FIXED JENKINS-16397] Just displaying /asynchPeople constructed the expensive People object merely to decide whether or not to display the “REST API” link.