Refactor index loading and harvest indexing.

Summary:
 - separate index/harvester configurations
 - decouple index/harvest loading from daemon interface.
 - fix mwsd not stopping while indexing harvests (closes #64)
 - simplified createCompressedIndex (closes #61)

Test Plan:
make test
bin/mwsd -I data/zbl
^C

Reviewers: radu.hambasan

Reviewed By: radu.hambasan

Differential Revision: http://phab.code4fun.de/D89