Merge branch 'develop' of https://github.com/ChuKuanYu/BTTE into develop
Merge branch 'piece_events' of https://github.com/ChuKuanYu/BTTE into piece_events
Create subdirs for src

1. Move source files (*.h *.cpp) of Peer Selection, Piece Selection
   and some general methods to algorithm/

2. Move util-related source files to utils/

3. lower case filenames
Modify Makefile to fit new dir-structure