Extract combo box common parts to super class to be able to reuse it in combo boxes that should not allow store related configurations

Signed-off-by: Alin Dreghiciu <adreghiciu@gmail.com>
Add support for named providers of List<SelectableEntryXO>

Signed-off-by: Alin Dreghiciu <adreghiciu@gmail.com>
Removed unused reference and injected Nexus.
Removed Nexus.

As actually not nexus but AppStatus is needed here.
Deprecated all of Nexus god object.
Removed last non-boot related bits from DefaultNexus.
Stop using Nexus god object.
Merge remote-tracking branch 'origin/master' into remove-god-object
Adapted test to changes
Removed all uses of Nexus and DEfaultNexus.

Introduced NxApplication component that is
lifecycle and takes care about boot process.
Merge pull request #140 from sonatype/named-providers

REVIEW: Named providers
Deadlock fix.

In this test the old Nexus component was implicitly looked
up -- hence Nx started -- as Resources did pull it in.

Since changes, now explicit start of Nx needed, otherwise
the waitForRoutingBackgroundUpdates() causes infinite
wait, since they did not even start.
[NEXUS-4997] Increase width of SMTP connection to fit TLS text

Signed-off-by: Alin Dreghiciu <adreghiciu@gmail.com>
Merge pull request #141 from sonatype/remove-god-object

NEXUS-5884 Remove use of Nexus god object
Merge remote-tracking branch 'origin/master' into remove-plexus