pkg-config added

The readme build and installation package requirements has been updated to reflect the requirements given in the docs.
zbeacon: uses only interfaces that are running

Adds a check in s_get_interface to ignore the interfaces that do not
have the IFF_UP flag set.
zbeacon: Ignore interfaces that are bonding slaves

Ignore interfaces that have the IFF_SLAVE flat set, if this flag is
defined.
Add _TRUNCATE define on zbeacon.c for some mingw compilers
Merge pull request #558 from TomorrowToday/master

pkg-config added
Merge pull request #559 from ahhentz/to_pull

zbeacon: uses only interfaces that are running
Merge pull request #560 from guidefloripa/master

Add _TRUNCATE define on zbeacon.c for some mingw compilers
Merge remote-tracking branch 'upstream/master'