Replacing all occurences of BITSd with "BITS server"

We had two BITSd in the project (one on the Fonera and the other on the Web server), and this could lead to ambiguities.
Replacing "closed"/"open" enum literals with class constants to avoid coding mistakes (e.g. "closed" versus "close").
Merge branch 'master' of github.com:esseks/bitsd