check if TrafficControl is enabled before testing imq module requirement.

This avoids failing to start in current OpenWrt Attitude Adjustment and trunk,
which lack IMQ support (and WONTFIX). Suggested in the issue discussed in:
http://ml.ninux.org/pipermail/nodogsplash/2013-May/000009.html

Signed-off-by: Gui Iribarren <gui@altermundi.net>
recognize yes, true or 1 as valid TrafficControl values

Signed-off-by: Gui Iribarren <gui@altermundi.net>
fix compiler warnings
disable all traffic control code when traffic_control is set to 0
removed unused icmp socket/ping code
use procd as OpenWrt tries to move away from init (available in current OpenWrt trunk), thanks @lynxis
clarify sentence
add conffiles
fix spelling and add reference to example configuration file
fix regression introduced in 73e5b8d (ref #18); revert all iptables -I/-A changes
make upload/download values returned by BinVoucher script call optional as claimed by the docs
update changelog and bump version
use similar format as in Debian changelog to ease syncing
use full name
fix readme, forgot to tell to select the NDS package
cleanup link list and add NDS mailing list
list available variables
udpate OpenWrt build instructions
make the variable $clientmac available in the splash site
prepend variable names