alias webtorrent.download to webtorrent.add

for parity with bittorrent-client
readme
add ip-set and load-ip-set to readme
use built-in blocklist handling of bittorrent-client
actually support https torrent urls
help message formatting
`webtorrent` module works with browserify (fix #88)
0.6.0
add usage to readme
Merge remote-tracking branch 'upstream/master'