INF cleanup: WIP
Merge remote-tracking branch 'origin/master' into item-not-found-cleanup
NEXUS-5511: Improve reasoning for INFEx

Implemented main cases.
NEXUS-5511: Improving some messages.
NEXUS-5511: Fixed broken messages.

Messages in two INFEx were constructed wrong.
Also, UT expectations fixed, aligned with actual message.
NEXUS-5511: Slipped UT for expectation fix
NEXUS-5511: Undoing indexer manager, as it has formatting issues.
NEXUS-5511: Cleanup
NEXUS-5511: Cleanup
Merge remote-tracking branch 'origin/master' into nexus-5511-improve-infex-reasoning
Merge remote-tracking branch 'origin/master' into nexus-5511-improve-infex-reasoning
NEXUS-5511: Applied comments and simplified
Merge remote-tracking branch 'origin/master' into nexus-5511-improve-infex-reasoning
NEXUS-5511: Not quite related.

Using SLF4J's new vararg method for logging
Merge remote-tracking branch 'upstream/master' into nexus-5511-improve-infex-reasoning
NEXUS-5511: Simplified

Changes:
* Removed not found reasons class, molded with INFex
* Reason now holds a "copy and detached" copy of request (static but mutable copy)
* ResourceStoreRequest does NOT track INF reasons anymore
* applied other comments, like removed INF reasoning with processors (processor will throw if needs that)
Merge remote-tracking branch 'origin/master' into nexus-5511-improve-infex-reasoning
Merge remote-tracking branch 'origin/master' into nexus-5511-improve-infex-reasoning
Merge remote-tracking branch 'origin/master' into nexus-5511-improve-infex-reasoning
Merge remote-tracking branch 'origin/master' into nexus-5511-improve-infex-reasoning

Conflicts:
	nexus-core/src/main/java/org/sonatype/nexus/proxy/maven/AbstractMavenRepository.java
	nexus-core/src/main/java/org/sonatype/nexus/proxy/maven/ChecksumContentValidator.java
	nexus-core/src/main/java/org/sonatype/nexus/proxy/repository/AbstractRepository.java