full text search index needs to be updated at user rename

[Robert Jäschke]

When a user account is renamed, the full text index needs to be updated, too.

Currently a search for the users posts with the new name does not return any results but with the old name does.

[Robert Jäschke]

This can be done in the same way the spammer flagging is implemented. I.e., there exists a method to tell Lucene that the posts of a user need to be updated.

[Robert Jäschke]

cf. [updatePredictions()](https://bitbucket.org/bibsonomy/bibsonomy/src/ed17782e99fb58f8e42373aee6f94670767db552/bibsonomy-lucene/src/main/java/org/bibsonomy/lucene/index/manager/LuceneResourceManager.java?at=default#cl-580]