[NEXUS-6790] Copy yum metadata to group in case of a single yum member

commit 733115040ee852a206e25fc8ed822c3d733cd9fb
Author: Alin Dreghiciu <adreghiciu@gmail.com>
Date:   Tue Oct 21 19:09:31 2014 +0300

    [NEXUS-6790] Fix test about conccurent running of MergeMetadataTask

commit 23886a203b7860cc04280dd5d68a00af474b4a23
Author: Alin Dreghiciu <adreghiciu@gmail.com>
Date:   Tue Oct 21 18:59:04 2014 +0300

    [NEXUS-6790] Only copy when there is exactly one member

commit 3be3e20300823cfc6f22db89ab82282f33736665
Author: Alin Dreghiciu <adreghiciu@gmail.com>
Date:   Tue Oct 21 18:19:34 2014 +0300

    [NEXUS-6790] Copy yum metadata to group in case of a single yum member

Conflicts:
	plugins/yum/nexus-yum-repository-plugin/src/test/java/org/sonatype/nexus/yum/internal/task/MergeMetadataTaskTest.java
Component ID generation/restoration service.
Trivial - using interface instead of impl in test.
Fixed comment.
Trivial: rename step 1
Trivial: rename part 2
Added a test, minor refactoring, license headers.
Parallel creation of nexus-component-services.
normalizing eof newline
Merge pull request #816 from sonatype/NEXUS-7518-component-id-service-clean

Merging based on +1s to PR #810.
Update styles of tabs
Merges in changes from master