network_traffic: allow to hide down interfaces

Interfaces which are down can be hidden or formatted differently.

The following options are added:
hide_down - whether to not display a interface which is down
format_down - format string if the interface is down (unless hide_down is set)
added options text_len and truncate_fields to mpd module for taming insanly long artist, album and song names
Add pianobar module
fixed pep8 issue
Fix blank lines and whitespaces
Add optional event_cmd bash file into the docs
network_traffic: do not hide by default down iface
Merge pull request #138 from simon04/network_traffic_down

network_traffic: allow to hide down interfaces
Merge pull request #139 from Arvedui/mpd_text_len

mpd text length
Merge pull request #140 from jlucchese/master

Add pianobar module
Fix #141
Aded 'keyboard_locks' module, to show CAPSLOCK, NUMLOCK and SCROLLLOCK status
Updated the docs
fix volume percentage
Merge pull request #144 from m0dprobe/master

fix volume percentage
Add uname module
uname: chop trailing newline
added ngb module
changed ip for internet ccheck to wikipedia