remove node 0.6 in travis
remove node 0.6 in travis

jay-bedeau-tc/oauth-1.0a,MartinMoizard/oauth-1.0a,sudoprime/oauth-1.0a,jay-bedeau-tc/oauth-1.0a,ddo/oauth-1.0a,MartinMoizard/oauth-1.0a,paulrutter/oauth-1.0a,sudoprime/oauth-1.0a