Mergin meas_json to master

Dear Alexander, I started to write the Wiki page for Meas_web. During this I just realized that because of some outstanding merges the installation of this tool is painfully complicated. In order to make things easier, I suggest to merge the meas_json part into OpenBSC master: http://cgit.osmocom.org/openbsc/log/?h=achemeris/meas_json Regards, Csaba