[GUI] revert contact -> buddy wording

PART 3

Change-Id: I389015ce0e0ab629398ea7a448e9f56e9f7b38a9
Reviewed-on: http://saros-build.imp.fu-berlin.de/gerrit/1189
Tested-by: Jenkins CI
Reviewed-by: Stefan Rossbach <srossbach@arcor.de>
[GUI] revert contact -> buddy wording

PART 4

Change-Id: I6f58a10d24b2eb248a077c89e4e40d539b11c528
Reviewed-on: http://saros-build.imp.fu-berlin.de/gerrit/1190
Tested-by: Jenkins CI
Reviewed-by: Stefan Rossbach <srossbach@arcor.de>