Weather: don't force specific grep location in bsd

It is possible that grep can be installed in any locations, 
so we should not just assume '/user/local/bin' on BSD machines.
We must rely on the user reading the manual and updating grep.
Merge pull request #141 from scicalculator/patch-1

Weather: don't force specific grep location in bsd
Warn if no weather location is specified.
Missed process settings call
Update AUTHORS.
Fixed DEFAULT_UNIT typo which caused non working unit setup
Merge pull request #144 from LubergAlexander/weather-segment

Fixed DEFAULT_UNIT typo which caused non working unit setup
added rainbarf segment
use "gsed" instead of "sed", if available
ifstat -z: Hides interface which counters are null, eg interfaces that are up but not used
Merge branch 'ifstat-mac' into creaktive
Merge pull request #146 from creaktive/ifstat-mac

ifstat segment made compatible with Mac OS X
Merge branch 'master' into rainbarf
configure rainbarf via ~/.rainbarf.conf
referenced rainbarf
Merge pull request #147 from creaktive/rainbarf

rainbarf segment support
Update AUTHORS
Info on how to solve multiple line issue in bash in README. Fixes #125.
Add pithos support for the now playing segment.
Added pithos to the list of supported players.