Revert g++ to 4.8.1 version for Travis
Revert g++ to 4.8.1 version for Travis

ychaim/dark-test-v2,Bitcoinsulting/dark-test-v2,Bitcoinsulting/multigateway-v2,ychaim/dark-test-v2,Bitcoinsulting/dark-test-v2,Bitcoinsulting/dark-test-v2,ychaim/dark-test-v2,mezzovide/btcd,Bitcoinsulting/dark-test-v2,mezzovide/btcd,ychaim/dark-test-v2,Bitcoinsulting/multigateway-v2,Bitcoinsulting/multigateway-v2,ychaim/dark-test-v2,mezzovide/btcd,mezzovide/btcd,Bitcoinsulting/dark-test-v2,ychaim/dark-test-v2,Bitcoinsulting/multigateway-v2,Bitcoinsulting/dark-test-v2,Bitcoinsulting/multigateway-v2,Bitcoinsulting/multigateway-v2,mezzovide/btcd,Bitcoinsulting/multigateway-v2,mezzovide/btcd,Bitcoinsulting/dark-test-v2,Bitcoinsulting/multigateway-v2,Bitcoinsulting/dark-test-v2,mezzovide/btcd,ychaim/dark-test-v2,mezzovide/btcd,Bitcoinsulting/multigateway-v2,mezzovide/btcd,ychaim/dark-test-v2