SB-137 XML & JSON serialization
#SB-137: Implement artifact searches via REST with XML/JSON results

Fixed the build.
SB-137 - indenting xml stream writer
SB-137 - indenting xml stream writer
#SB-137: Implement artifact searches via REST with XML/JSON results

- Made the XMLStreamWriter flush.
SB-137 pretty print, multi repo
#SB-137: Implement artifact searches via REST with XML/JSON results
- Polished up the code a bit.
- Removed commented out code.
- Made the search produce proper results that work with multiple repositories and storages.
- Refactored the ArtifactClient a bit.

#SB-57: Implement basic artifact searching classes
Implemented:
- SearchRequest
- SearchResults
- ArtifactSearchService
- ArtifactSearchServiceImpl

General:
- Fixed some storage/repository issues which were otherwise going to further develop into bugs.
- Added a baseUrl to the strongbox.xml so that it coule be used for search results (among other things).
#SB-137: Implement artifact searches via REST with XML/JSON results
- Added a simple method to the ResourceCloser to further reduce boiler-plate code.
Merge branch 'SB-137'
#SB-136: Implement checking if an artifact exists in a proxy repository's index

Implemented.
#SB-136: Implement checking if an artifact exists in a proxy repository's index

Fixed the tests.
Merge pull request #14 from strongbox/SB-136

SB-136: Implement checking if an artifact exists in a proxy repository's index
Merge branch 'master' into SB-213

Conflicts:
	strongbox-storage/strongbox-storage-indexing/src/main/java/org/carlspring/strongbox/booters/StorageBooter.java
	strongbox-storage/strongbox-storage-indexing/src/main/java/org/carlspring/strongbox/storage/indexing/RepositoryIndexManager.java
	strongbox-storage/strongbox-storage-indexing/src/test/java/org/carlspring/strongbox/storage/indexing/RepositoryIndexerTest.java
	strongbox-testing/strongbox-testing-storage-resources/strongbox-testing-storage-indexing-resources/src/main/resources/META-INF/spring/strongbox-storage-indexing-context.xml
	strongbox-web-core/src/main/java/org/carlspring/strongbox/rest/SearchRestlet.java