Stabilizing the IT

It seems that backgrounded auto-routing
jobs are not always able to keep up. Explicitly
waiting for them before checking conditions.
[NX-229] Allow filtering of repository targets
NX-390: avoid package overlap between nexus-webresources-api and nexus-webresources-plugin
NX-390: these utility/filter classes are used by several plugins, so should be non-internal
NX-390: this utility class belongs in the webresources plugin
NX-390: RemoteStorageContextCustomizer is used by several plugins, so should be non-internal
NX-390: these conditions and validators are used by several plugins, so should be non-internal
NX-390: don't rely on internal goodies class, inject it by name
NX-390: support lookup of nexus.properties from the current class context, rather than the nexus-bootstrap class (which may be in a different bundle)
NX-390: detect plugins by their use of the Nexus plugin API, rather than the legacy META-INF/nexus/plugin.xml resource