add closeQuietly method for repository session when only reading we can ignore this error.

git-svn-id: https://svn.apache.org/repos/asf/archiva/trunk@1447103 13f79535-47bb-0310-9956-ffa450edef68
add javadoc

git-svn-id: https://svn.apache.org/repos/asf/archiva/trunk@1447104 13f79535-47bb-0310-9956-ffa450edef68