[MRM-1871] ConcurrentModificationException in DefaultRepositoryProxyConnectors
create a copy to avoid ConcurrentModificationException
[MRM-1871] copy List before sorting it
format and debug infos
[MRM-1390] Add REST methods to search JCR store for generic metadata and properties

Added REST methods:

artifactsByProjectVersionMetadata/{key}/{value}
artifactsByMetadata/{key}/{value}
artifactsByProperty/{key}/{value}
searchArtifacts/{text}
searchArtifacts/{key}/{text}

In JCR implementation When searching into any property (key = nil) we can't do exact searchs
[MRM-1390] Implement search methods for generic metadata and properties in Cassandra store

Some caveats with Cassandra implementation:

We can't search artifacts by any (wildcard) property, so searchArtifacts(text,...) just calls getArtifactsByMetadata
The exact parameter is ignored as we can't do non exact searches in Cassandra
[MRM-1390] Cassandra: rename Metadata Facet column 'key' to 'facetKey'

The column 'key' can't be queried in Cassandra
Probably because 'key' is reserved for the element key or a limitation in Hector
[MRM-1390] Bump version to 2.2.0