Build and instruction fixes

[anoadragon453]

Hello there, noticed a couple things off with the repo and fixed them up. This includes:

• Correctly have libtorrent as a git submodule
• Change clone to use HTTPS instead (got a permission denied error using git@...:rllola) and to use --recursive (so the submodules are downloaded)
• Change build instructions to use all available cores (faster building times)
• Some small grammatical fixes

[anoadragon453]

I will say that I do get the following error when starting up ZeroNet though:

user@dev:~/ZeroBundle$ ./ZeroNet.sh 
- Starting ZeroNet...
[12:51:10] - OpenSSL loaded, version: 01000207F
[12:51:10] PluginManager Plugin Torrent load error: ImportError: No module named libtorrent in PluginManager.py line 39 > __init__.py line 1 > TorrentPlugin.py line 2
[12:51:10] - Patching sockets to tor socks proxy: 127.0.0.1:9050
[12:51:10] - Version: 0.5.6 r2121, Python 2.7.11 |Continuum Analytics, Inc.| (default, Dec  6 2015, 18:08:32) 

Is the libtorrent folder more than just the libtorrent source code? I've also installed python-libtorrent from apt but no success, it still can't import libtorrent for whatever reason...

EDIT: Figured it out, ZeroBundle uses it's own Python binary...