Remove gcc 4.6 from travis matrix
Remove gcc 4.6 from travis matrix

appleseedhq/appleseed,Biart95/appleseed,aytekaman/appleseed,Aakash1312/appleseed,appleseedhq/appleseed,glebmish/appleseed,gospodnetic/appleseed,aiivashchenko/appleseed,luisbarrancos/appleseed,aiivashchenko/appleseed,appleseedhq/appleseed,gospodnetic/appleseed,gospodnetic/appleseed,glebmish/appleseed,dictoon/appleseed,luisbarrancos/appleseed,Aakash1312/appleseed,Vertexwahn/appleseed,Vertexwahn/appleseed,Vertexwahn/appleseed,aytekaman/appleseed,est77/appleseed,glebmish/appleseed,aiivashchenko/appleseed,Vertexwahn/appleseed,glebmish/appleseed,gospodnetic/appleseed,gospodnetic/appleseed,pjessesco/appleseed,aiivashchenko/appleseed,Aakash1312/appleseed,appleseedhq/appleseed,dictoon/appleseed,est77/appleseed,luisbarrancos/appleseed,Aakash1312/appleseed,pjessesco/appleseed,Biart95/appleseed,aytekaman/appleseed,luisbarrancos/appleseed,Aakash1312/appleseed,est77/appleseed,pjessesco/appleseed,dictoon/appleseed,luisbarrancos/appleseed,aytekaman/appleseed,aytekaman/appleseed,Biart95/appleseed,dictoon/appleseed,pjessesco/appleseed,dictoon/appleseed,appleseedhq/appleseed,est77/appleseed,pjessesco/appleseed,Vertexwahn/appleseed,est77/appleseed,aiivashchenko/appleseed,Biart95/appleseed,Biart95/appleseed,glebmish/appleseed