Reformat, no code change.
NEXUS-5749: Scheduled tasks dissappears

Multiple problems were probably doing it
* any runtime exception while gathering userId aborts config save
* pool thread got "polluted" by inherited Subjects
* scheduled thread subject was set "too deep", some homework by scheduler
was done outside of it.
* probably NEXUS-5728 caused that inherited subjects become invalid
NEXUS-5749: Reshuffled

To make scheduler not need any extra deps (shiro, guava),
extracted the scheduler stuff from it, and made Nx core
provide the needed one.
Merge remote-tracking branch 'origin/master' into nexus-5749-scheduled-tasks-dissappears
NEXUS-5749: Added Qualifier

And removed clumsy provider
Merge remote-tracking branch 'origin/master' into nexus-5749-scheduled-tasks-dissappears
NEXUS-5749: Added override
Fixing UTs
Revert to plain Named.

Which I dislike, but it works...
Reverted to plexus components

Still no go, for some reason the real
realms are not picked up in UTs and 2 of them
fail
Merge remote-tracking branch 'origin/master' into nexus-5749-scheduled-tasks-dissappears
Merge remote-tracking branch 'origin/master' into nexus-5749-scheduled-tasks-dissappears
Huge cleanup.

Changes:
* removed deprecated security stuff (some tests were still using it!)
* removed deprecated MimeUtil component, a memory hog
* cleaned up Security (base and realms) tests
* cleaned up Nx Core tests wrt use of Security, it was mess
* NexusAppTestSupport class made to be used for tests needing security, added proper cleanup
* changed/relocated some tests in class hierarchy (some test moved "lower" not needing security, other put under NexusAppTestSupport)
* Fixed nexus-security dependency, commons-beanutils needed by Shiro, but is excluded in buildsupport-shiro
*
Merge remote-tracking branch 'origin/master' into nexus-5749-scheduled-tasks-dissappears
Unused imports
License and javadoc
Another bad test superclass.

That relied on deprecated security
stuff and did not use the SecurityModule,
nor was doing cleanup as expected.

Also, PlexusTestCaseSupport should be used,
not the "vanilla" from the sisu-inject-plexus
one.
Legacy TL test ignored for now
Merge remote-tracking branch 'origin/master' into nexus-5749-scheduled-tasks-dissappears

Conflicts:
	components/nexus-core/src/test/java/org/sonatype/nexus/NexusAppTestSupport.java
	components/nexus-core/src/test/java/org/sonatype/nexus/proxy/AbstractNexusTestEnvironment.java
	components/nexus-core/src/test/java/org/sonatype/nexus/proxy/AbstractProxyTestEnvironment.java
	components/nexus-core/src/test/java/org/sonatype/nexus/proxy/RequestFlagsTest.java
	components/nexus-core/src/test/java/org/sonatype/nexus/proxy/maven/metadata/mercury/MergeOperationTest.java
	components/nexus-core/src/test/java/org/sonatype/scheduling/DefaultTaskConfigManagerTest.java
	components/nexus-security-realms/src/test/java/org/sonatype/security/EmptyRoleTest.java
	components/nexus-security/src/test/java/org/sonatype/security/realms/SecurityAuthenticationTest.java
	plugins/indexer/nexus-indexer-lucene-plugin/src/test/java/org/sonatype/nexus/index/Nexus3578IndexerManagerIT.java
	plugins/restlet1x/nexus-restlet1x-plugin/src/test/java/org/sonatype/security/rest/users/AbstractSecurityRestTest.java
Undoing merge peculiarities